Assume the random variable x is normally distributed with mean u=87 and standard deviation o=5. Find the indicated probability.

P(x<81)

P(x<81)=__(Round to four decimal places).

Answers

Answer 1

Looking up the z-score of -1.2 in the table, we find that the probability P(x < 81) ≈ 0.1151 (rounded to four decimal places).
So, P(x < 81) = 0.1151.

Given that the random variable x is normally distributed with a mean (µ) of 87 and a standard deviation (σ) of 5, we are asked to find the probability P(x < 81).

To solve this problem, we need to use the standard normal distribution table or a calculator that has the capability to calculate probabilities for a normal distribution.

First, we need to standardize the random variable x by subtracting the mean and dividing by the standard deviation. This process will give us the z-score for x.

z = (x - u) / o

In this case, we have:

z = (81 - 87) / 5 = -1.2

Now, we can use the standard normal distribution table or a calculator to find the probability of getting a z-score less than -1.2.

Using a standard normal distribution table, we find that the probability of getting a z-score less than -1.2 is 0.1151 (rounded to four decimal places).

Therefore, the probability of getting a value of x less than 81 is approximately 0.1151.

P(x<81) = 0.1151 (rounded to four decimal places).

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Related Questions

describe the behavoir of the markov chain with starting vector [1,0,0]. are there any stable vectors

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The behavior of the Markov chain with starting vector [1,0,0] can be analyzed by calculating the transition probabilities and the resulting probability distribution at each step. The existence of stable vectors depends on the limiting probabilities, which can be calculated to determine if there is a unique stable vector.

A Markov chain is a stochastic process that models a system that transitions from one state to another based on some predefined probabilities. In this case, the starting vector [1,0,0] represents the probability distribution of the system being in each state at the beginning of the process. The first element of the vector represents the probability of being in state 1, the second element represents the probability of being in state 2, and the third element represents the probability of being in state 3.

As the Markov chain progresses, the system transitions from one state to another based on the transition probabilities. The behavior of the Markov chain with starting vector [1,0,0] can be analyzed by calculating the transition probabilities and the resulting probability distribution at each step.

There may or may not be stable vectors in the Markov chain. A stable vector is a probability distribution that remains constant over time, regardless of the starting vector. In other words, if the Markov chain starts from any initial state, it will eventually converge to the stable vector.

To determine if there are any stable vectors in the Markov chain, we need to calculate the limiting probabilities for each state. If the limiting probabilities exist and are the same for all initial vectors, then there is a unique stable vector. If the limiting probabilities do not exist or are different for different initial vectors, then there is no stable vector.

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Exercise 2.2.8 :

Solve y’’ − 8y’ + 16y = 0 for y(0) = 2, y’(0) = 0

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The solution to the differential equation with the given initial conditions is: y = 2 e^(4t) - (1/2) t e^(4t)

To solve this differential equation, we first find the characteristic equation by assuming a solution of the form y = e^(rt). Plugging this into the differential equation, we get:

r^2 e^(rt) - 8re^(rt) + 16e^(rt) = 0

Factoring out the e^(rt) term, we get:

e^(rt) (r^2 - 8r + 16) = 0

The quadratic equation r^2 - 8r + 16 = 0 has a double root of r = 4. Therefore, the general solution to the differential equation is:

y = c1 e^(4t) + c2 t e^(4t)

To solve for the constants, we use the initial conditions. First, we have y(0) = 2, which gives us:

c1 = 2

Next, we have y'(0) = 0, which gives us:

c1 (4) + c2 (0) = 0

Solving for c2, we get:

c2 = -c1/4 = -1/2

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A tree casts a shadow of 15 meters, while a 2-meter post nearby casts a shadow of 3 meters. How tall is the tree

Answers

The tree is 10 meters tall.

To find the height of the tree, we can use the concept of similar triangles. The ratio of the height of the tree to the length of its shadow should be equal to the ratio of the height of the post to the length of its shadow, since they are both located in the same plane and are being illuminated by the same light source.

Let's use proportions to solve this problem. We can set up the proportion:

height of tree / length of tree's shadow = height of post / length of post's shadow

Let h be the height of the tree. Then we have:

h / 15 = 2 / 3

Cross-multiplying, we get:

3h = 30

h = 10

Therefore, the tree is 10 meters tall.

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The mean number of words per minute (WPM) read by sixth graders is 8989 with a standard deviation of 1616 WPM. If 6666 sixth graders are randomly selected, what is the probability that the sample mean would be greater than 92.2592.25 WPM

Answers

The probability of obtaining a sample mean greater than 92.25 WPM is extremely small, approaching zero.

What is the probability of obtaining a sample mean greater than 92.25 WPM, given a population mean of 8989 WPM and a standard deviation of 1616 WPM?

We can use the Central Limit Theorem to solve this problem, since we have a large sample size (n=6666) and a known population mean (μ=8989) and standard deviation (σ=1616).

The Central Limit Theorem states that the distribution of the sample means will be approximately normal with a mean of μ and a standard deviation of σ/√n.

So, for this problem:

The sample size is n=6666The population mean is μ=8989The population standard deviation is σ=1616

We want to find the probability that the sample mean would be greater than 92.25 WPM, which we can convert to a z-score using the formula z = (x - μ) / (σ / √n), where x is the sample mean.

z = (92.25 - 8989) / (1616 / √6666) = -116.45

Now, we can use a standard normal distribution table or a calculator to find the probability that a standard normal random variable is greater than -116.45. Since this probability is extremely small (essentially zero), we can conclude that the probability of getting a sample mean greater than 92.25 WPM is also essentially zero.

Therefore, the answer to the problem is that the probability of getting a sample mean greater than 92.25 WPM is essentially zero, or very close to 0.

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In a sample of 34 iPhones, 21 had over 94 apps downloaded. Construct a 90% confidence interval for the population proportion of all iPhones that obtain over 94 apps. Assume z0.05

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To construct a 90% confidence interval for the population proportion of all iPhones that obtain over 94 apps, we first need to calculate the sample proportion: p = 21/34 = 0.618.



Next, we need to determine the standard error of the proportion: SE = √(p(1-p)/n) = √(0.618(1-0.618)/34) = 0.097
Using a z-score of 1.645 (corresponding to a 90% confidence level), we can calculate the margin of error:
ME = z*SE = 1.645*0.097 = 0.160.



Finally, we can construct the confidence interval: p ± ME = 0.618 ± 0.160 = (0.458, 0.778)
Therefore, we can be 90% confident that the true proportion of all iPhones that obtain over 94 apps is between 0.458 and 0.778.


To construct a 90% confidence interval for the population proportion of all iPhones that obtain over 94 apps, we will use the following formula: CI = p ± z * √(p(1-p)/n), Here, p is the sample proportion, z is the z-score for the given confidence level, and n is the sample size.



First, we calculate the sample proportion (p): p = (Number of iPhones with over 94 apps) / (Total number of iPhones in the sample) = 21/34 ≈ 0.6176, For a 90% confidence interval, the z-score (z) is given as 1.645 (since z0.05 = 1.645).
Now, we can plug the values into the formula:


CI = 0.6176 ± 1.645 * √(0.6176 * (1 - 0.6176) / 34)
CI = 0.6176 ± 1.645 * √(0.2361 / 34)
CI = 0.6176 ± 1.645 * 0.0790
CI = 0.6176 ± 0.1301



Thus, the 90% confidence interval for the population proportion of all iPhones that obtain over 94 apps is approximately (0.4875, 0.7477).

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In a Chi-square analysis, what general condition causes one to reject (fail to accept) the null hypothesis

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In a Chi-square analysis, one rejects (or fails to accept) the null hypothesis when the calculated Chi-square test statistic (χ²) is greater than the critical value, indicating that there is a significant difference between the observed and expected frequencies.

In a chi-square analysis, the null hypothesis is that there is no significant difference between the observed frequencies and the expected frequencies.

The expected frequencies are usually calculated assuming a specific distribution or model.

To determine whether to reject or fail to accept the null hypothesis, we compare the calculated chi-square statistic to a critical value obtained from a chi-square distribution table with a specified degrees of freedom.

The degrees of freedom are calculated as (number of categories - 1).

If the calculated chi-square value is greater than the critical value, it means that the observed frequencies differ significantly from the expected frequencies and that the null hypothesis can be rejected at a certain level of significance (usually 0.05 or 0.01).

In other words, if the chi-square statistic is larger than the critical value, it suggests that the observed data is unlikely to have arisen by chance, and that there is evidence to support the alternative hypothesis, which states that there is a significant difference between the observed and expected frequencies.

On the other hand, if the calculated chi-square value is less than or equal to the critical value, it means that there is no significant difference between the observed and expected frequencies and that the null hypothesis cannot be rejected.

This typically occurs when the p-value associated with the test statistic is less than the predetermined significance level (α), such as 0.05 or 0.01, suggesting that the observed result is unlikely to have occurred by chance alone.

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Show that the normal line at any point of the circle x^2+y^2 = a^2 passes through the origin.

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The  point (x0, y0) lies on the line passing through the origin, and hence the normal line to the circle at P passes through the origin.

Let P = (x0, y0) be any point on the circle x^2 + y^2 = a^2.

The gradient of the tangent to the circle at P is given by dy/dx = -x0/y0.

Therefore, the gradient of the normal to the circle at P is given by -y0/x0.

Using the point-slope equation of a line, the equation of the normal line passing through P is y - y0 = (-x0/y0)(x - x0).

To show that this line passes through the origin, we need to substitute x = 0 and y = 0 into the equation of the line and show that it satisfies the equation.

Substituting x = 0, we get y - y0 = 0, which gives y = y0.

Substituting y = 0, we get -x0(x - x0)/y0 = 0, which gives x = x0.

Therefore, the point (x0, y0) lies on the line passing through the origin, and hence the normal line to the circle at P passes through the origin.

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I just need the answers of all of them please

Answers

The number of sweaters in the data is 10 and other statistical measures are computer below

Calculating the statistical measures

The number of sweaters in the data

This is the total frequency represented in the dot plot

So, we have

Sweaters = 10

The mean, median and mode

The mean is calculated as

Mean = Sum/count

So, we have

Mean = (25 + 25 + 25 + 25 + 30 + 30 + 40 + 40 + 45 + 65)/10

Mean = 35

For the median, we have

Median = (30 + 30)/2

Median = 30

For the mode, we have

Mode = 25

The quartiles

From the dataset, we have

Q1 = (25 + 25)/2

Q1 = 25

Q3 = (40 + 45)/2

Q3 = 42.5

Next, we have

IQR = 42.5 - 25

IQR = 17.5

Are there outliers?

Yes, there are outliers in the plot

And the outlier is 65

This is because 65 is relatively far from other values

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Resultado de la permutación 7p3

Answers

The permutation value is 210.

We have,

A permutation of a set of objects is any arrangement of those objects in a specific order.

The number of permutations of a set of n objects is denoted by nPn or n!, which represents the factorial of n.

For example, if there are four objects, there are 4! = 4 x 3 x 2 x 1 = 24 possible permutations of those objects.

Now,

[tex]^7P_3[/tex]

= 7!/3!

= 7 x 6 x 5 x 4 x 3! / 3!

= 7 x 6 x 5 x 4

= 210

Thus,

The permutation value is 210.

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The complete question.

Result of permutation [tex]^7P_3[/tex]

A machine is shut down for repair if a random sample of 100 items selected from the daily output of the machine reveals at least 15% defectives. Assume that daily output is a large number of items. If on one given day the machine is producing only 10% defective items, what is the probability that it will be shut down

Answers

Thus, the probability that the machine will be shut down for repair on a day when it is producing only 10% defective items is 3.3%.

The problem statement gives us a threshold of at least 15% defectives for the machine to be shut down for repair. This implies a binomial distribution with n = 100 and p >= 0.15.

Given that the machine is producing only 10% defective items on a given day, we need to find the probability of the sample having at least 15% defectives.

Using the binomial distribution formula, we can calculate the probability of having k or more defectives in a sample of size n with probability of success p:

P(X >= k) = 1 - P(X < k)
where P(X < k) = Σ (n choose i) * p^i * (1-p)^(n-i) for i = 0 to k-1

Plugging in the values, we get:

P(X >= 15) = 1 - P(X < 15)
= 1 - Σ (100 choose i) * 0.1^i * 0.9^(100-i) for i = 0 to 14

Using a calculator or statistical software, we can compute this probability to be approximately 0.033 or 3.3%.

Therefore, the probability that the machine will be shut down for repair on a day when it is producing only 10% defective items is 3.3%.

This suggests that the machine is not very likely to be shut down for repair on such a day, but it is still possible. The management may want to keep monitoring the production and take appropriate actions if the defect rate increases in the future.

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According to the empirical rule, the bell or mound shaped distribution will have approximately 68% of the data within what number of standard deviations of the mean

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The correct option is option a) One standard deviation.

According to the empirical rule, the bell or mound shaped distribution will have approximately 68% of the data within one standard deviations of the mean.

According to the empirical rule, the bell or mound-shaped distribution will have approximately 68% of the data within one standard deviation of the mean. This means that if the data is normally distributed, then about 68% of the data points will fall within one standard deviation above or below the mean.

Similarly, the empirical rule states that approximately 95% of the data will fall within two standard deviations of the mean, and about 99.7% of the data will fall within three standard deviations of the mean.

This means that if the data is normally distributed, then 95% of the data points will fall within two standard deviations above or below the mean, and 99.7% of the data points will fall within three standard deviations above or below the mean.

It is important to note that the empirical rule is based on the assumption that the data is normally distributed. If the data does not follow a normal distribution, then the empirical rule may not apply.

Therefore, the answer to the question is (a) One standard deviation, (b) Two standard deviations, and (c) Three standard deviations. Option (d) Four standard deviations and (e) Four standard deviations are not correct, and option (f) None of the above is partially correct as it excludes options (a), (b), and (c), but option (g) All of the above is not correct as options (d) and (e) are incorrect.

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What is the outlier in the scatterplot above? Type your answer in (x, y) format.

Answers

Answer:

The answer to your problem is, ( 22, 21 )

Step-by-step explanation:

You can look at the picture to see how I did it.

What an outlier is, when a point a piece of graph is “ separate “ from its other graphs or in this case ‘ points ‘

Example:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~1 hour    2 hour    3 hour    6 hour

  4            3                2            1

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We can see that 6 is the outlier.

Thus the answer to your problem is, ( 22, 21 )

Picture:

Find the mean, median, and mode for the sample whose observations, 15, 7, 8, 95, 19, 12, 8, 22, and 14, represent the number of sick days claimed on 9 federal income tax returns. Which value appears to be the best measure of the center of these data

Answers

The mean is found by adding all the observations and dividing by the number of observations, so in this case, (15+7+8+95+19+12+8+22+14)/9 = 22. The middle observation is 14, so that is the median. The mode is the most frequently occurring observation, so in this case, the mode is 8, since it occurs twice.

It's difficult to say which measure of center is the best without more information about the distribution of the data and the purpose for which the information is being used. If the data is relatively symmetric and not skewed by extreme values, the mean may be a good measure of center. However, if the data is skewed or has extreme values, the median may be a better measure of center. The mode is useful when we want to know the most common observation. Ultimately, the best measure of center depends on the specific situation and what information is most important to the decision-making process.


To find the mean, median, and mode for this sample, follow these steps:

1. First, arrange the data in ascending order: 7, 8, 8, 12, 14, 15, 19, 22, 95.

2. To find the mean (average), sum the values and divide by the number of observations:
(7+8+8+12+14+15+19+22+95)/9 = 200/9 ≈ 22.22.

3. To find the median (middle value), locate the value that is in the middle of the ordered list:
There are 9 values, so the median is the 5th value, which is 14.

4. To find the mode (most frequent value), identify the value that occurs the most:
The value 8 appears twice, so the mode is 8.

Mean: 22.22
Median: 14
Mode: 8

In this case, the median (14) seems to be the best measure of the center of these data because it is less affected by the outlier (95) than the mean. The mode (8) represents only the most frequent value and does not account for other values in the dataset.

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21. Suppose that every student in a discrete mathematics class of 25 students is a freshman, a sophomore, or a junior. a) Show that there are at least nine freshmen, at least nine sophomores, or at least nine juniors in the class. b) Show that there are either at least three freshmen, at least 19 sophomores, or at least five juniors in the class.

Answers

(a) The total number of students would be less than 27. There must be at least nine freshmen, sophomores, or  juniors in the class.

(b) There must be at least three freshmen, at least 19 sophomores, or at least five juniors in the class.

How to find at least nine freshmen, sophomores, or juniors in the class?

a) Let's assume that there are less than nine freshmen, less than nine sophomores, and less than nine juniors in the class.

Then the total number of students would be less than 9+9+9=27, which is a contradiction because we were given that there are 25 students in the class.

Therefore, there must be at least nine freshmen, at least nine sophomores, or at least nine juniors in the class.

How to find freshmen, sophomores, or  juniors in the class?

b) Let's assume that there are less than three freshmen, less than 19 sophomores, and less than five juniors in the class.

Then the total number of students would be less than 3+19+5=27, which is a contradiction because we were given that there are 25 students in the class.

So, we know that there must be at least three freshmen, at least 19 sophomores, or at least five juniors in the class. Suppose that there are less than three freshmen and less than 19 sophomores in the class.

Then there must be at least 25 - (3+19) = 3 juniors in the class. This contradicts our assumption that there are less than five juniors in the class.

Similarly, suppose that there are less than three freshmen and less than five juniors in the class. Then there must be at least 25 - (3+5) = 17 sophomores in the class. This contradicts our assumption that there are less than 19 sophomores in the class.

Finally, suppose that there are less than five juniors and less than 19 sophomores in the class. Then there must be at least 25 - (5+19) = 1 freshman in the class. This contradicts our assumption that there are less than three freshmen in the class.

Therefore, there must be at least three freshmen, at least 19 sophomores, or at least five juniors in the class.

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Find the arclength of the curve r(t)=< 2t^2 , 2*sqrt(2) t , ln(t) > , for 1<= t <= 10. L =

Answers

The  approximate arclength of the curve is L ≈ 34.179 units.

To find the arclength of the curve, we need to integrate the magnitude of the curve's derivative with respect to t over the given interval [1, 10].

The derivative of r(t) is:

r'(t) = < 4t, 2*sqrt(2), 1/t >

The magnitude of r'(t) is:

|r'(t)| = sqrt((4t)^2 + (2*sqrt(2))^2 + (1/t)^2) = sqrt(16t^2 + 8 + 1/t^2)

Thus, the arclength of the curve is given by:

L = ∫[1,10] |r'(t)| dt
 = ∫[1,10] sqrt(16t^2 + 8 + 1/t^2) dt

This integral cannot be evaluated in terms of elementary functions, but we can approximate it using numerical methods. One approach is to use Simpson's rule, which approximates the integral as:

L ≈ ∆t/3 * [f(1) + 4f(3) + 2f(5) + ... + 4f(9) + f(10)]

where ∆t = (10 - 1)/n is the step size and f(t) = sqrt(16t^2 + 8 + 1/t^2). Using n=100, we get:

L ≈ 34.179

Therefore, the approximate arclength of the curve is L ≈ 34.179 units.

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The use of 1s and 0s to represent information is characteristic of a(n) ____________________ system.

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The use of 1s and 0s to represent information is characteristic of a binary system.

A binary number is a number that is expressed using the base-2 numeral system, often known as the binary numeral system, which employs only two symbols, typically "0" and "1". With a radix of 2, the base-2 number system is a positional notation. A bit, or binary digit, is the term used to describe each digit. One of the four different kinds of number systems is the binary number system. Binary numbers are exclusively represented by the two symbols or digits 0 (zero) and 1 (one) in computer applications. Here, the base-2 numeral system is used to represent the binary numbers. One binary number is (101)2, for instance.

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Compute the tolerance interval for capturing at least 90% of the values in a normal distribution with the confidence level of 95%. Round your answers to two decimal places (e.g. 98.76).

Answers

Thus, with 95% confidence that at least 90% of the values in a normal distribution fall within the tolerance interval of mean +/- 0.10.


We can use a standard normal distribution table to find the critical values, which is the z-score that corresponds to the given confidence level. For a 95% confidence level, the critical value is 1.96.

Next, we need to find the standard deviation of the normal distribution. We can use the formula:
tolerance interval = mean +/- z * (standard deviation / sqrt(n))

where mean is the mean of the distribution, z is the critical value, standard deviation is the standard deviation of the distribution, and n is the sample size. Since we don't have a sample size, we can assume a large sample size and use the population standard deviation instead.

Assuming a population standard deviation of 1, the tolerance interval is:
tolerance interval = mean +/- 1.96 * (1 / √(n))

To capture at least 90% of the values, we need to set the tolerance interval to be equal to 90%.
0.90 = 1.96 * (1 / √(n))

Solving for n, we get:
n = (1.96 / 0.10)^2
n = 384.16

Since we assumed a large sample size, we can round up to the nearest integer, which gives us a sample size of 385.

The tolerance interval for capturing at least 90% of the values in a normal distribution with a confidence level of 95% and a sample size of 385 is:
tolerance interval = mean +/- 1.96 * (1 / √t(385))

This can be simplified to:
tolerance interval = mean +/- 0.10

Therefore, we can say with 95% confidence that at least 90% of the values in a normal distribution fall within the tolerance interval of mean +/- 0.10.

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A researcher measures the time it takes eight participants to complete three successive tasks. What are the degrees of freedom between persons for a one-way repeated-measures ANOVA

Answers

In a one-way repeated-measures ANOVA, we are testing for differences between the means of three or more related groups (in this case, the three successive tasks) with the same participants (in this case, the eight participants).

The degrees of freedom between persons are calculated as follows:

df_between = k - 1

where k is the number of groups (in this case, the number of participants), and -1 represents the constraint that the overall mean must be calculated from the group means.

Since there are eight participants in this study, the degrees of freedom between persons for a one-way repeated-measures ANOVA would be:

df_between = 8 - 1 = 7

Therefore, there are 7 degrees of freedom between persons in this study.

A political candidate has asked you to conduct a poll to determine what percentage of people support her.

If the candidate only wants a 5% margin of error at a 99% confidence level, what size of sample is needed?

Give your answer in whole people.

ME=8%=0.08

CL=90%=1.645

n=?

n=(z*/m)+p*(1-p*)= (1.645/0.08)+(0.5)x(1-0.5)= 423.0664063=423

Answers

The political candidate with a 5% margin of error at a 99% confidence level, a sample size of 423 people is needed.

To determine what percentage of people support the political candidate, a poll needs to be conducted. The candidate has requested a 5% margin of error at a 99% confidence level. This means that the results should be accurate within 5% of the actual percentage, and the researcher can be 99% confident that the results reflect the opinions of the entire population.

To calculate the sample size needed, the margin of error and confidence level must be taken into account. Using the formula n=(z*/m)+p*(1-p*), where n is the sample size, z* is the z-score for the desired confidence level, m is the margin of error, and p* is the estimated proportion of support (0.5 for an unbiased estimate), the sample size can be determined.

For a 99% confidence level, the z-score is 1.645. The margin of error is 5%, or 0.08 as a decimal. Using these values, the formula becomes n=(1.645/0.08)+(0.5)x(1-0.5), which simplifies to n=423.067. Rounded to the nearest whole number, the sample size needed is 423 people.

In summary, to determine what percentage of people support the political candidate with a 5% margin of error at a 99% confidence level, a sample size of 423 people is needed.

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Find the probability that a 13-card hand (from a 52-card deck) has exactly 3 three-of-a-kinds (no 4-of-akinds and no pairs).

Answers

The probability that a 13-card hand (from a 52-card deck) has exactly 3 three-of-a-kinds (no 4-of-a-kinds and no pairs) is approximately 0.0000266 or 0.0266%.

To calculate this probability, we can first find the number of possible hands that meet the criteria. There are 13 possible ranks for the three-of-a-kinds, and for each rank, we must choose 3 out of the 4 cards of that rank.

There are then 10 remaining ranks that can be used for the other cards, and for each of these ranks, we must choose 1 out of the 4 cards of that rank. Thus, the total number of possible hands with exactly 3 three-of-a-kinds is:

(13 choose 1) * (4 choose 3)^3 * (10 choose 10) * (4 choose 1)^10 = 3,168,192

Next, we find the total number of possible 13-card hands from a 52-card deck:

(52 choose 13) = 635,013,559,600

Finally, we divide the number of possible hands with exactly 3 three-of-a-kinds by the total number of possible hands:

3,168,192 / 635,013,559,600 ≈ 0.0000266 ≈ 0.0266%

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In a Random Forest model, each tree is fitted using: Group of answer choices A few randomly chosen rows and randomly chosen columns All predictors and all rows A few randomly chosen rows and all columns All rows and randomly chosen columns

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In a Random Forest model, each tree is fitted using a few randomly chosen rows and randomly chosen columns. This process is known as "bagging".

Random Forest is a popular machine learning algorithm that belongs to the family of ensemble learning methods. It combines multiple decision trees and creates a forest of trees, hence the name "Random Forest". The goal of this algorithm is to improve the accuracy and robustness of the individual decision trees by reducing their tendency to overfit the data. Random Forest works by randomly selecting a subset of features and data samples from the original dataset and constructing a decision tree on each of these subsets.

The final output is the average prediction made by all the decision trees in the forest. Random Forest has several advantages, including high accuracy, robustness, and ability to handle large datasets. It can be used for both classification and regression problems, and it is particularly effective in dealing with missing data and noisy data. Overall, Random Forest is a powerful and flexible algorithm that has found wide applications in various fields, including finance, healthcare, and marketing.

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You would like to compare mathematics knowledge among 15-year-olds in the US and Japan. To do this, you plan to give a mathematics achievement test to samples of 1000 15-year-olds in each of the two countries. To ensure that the samples will include individuals from all different socioeconomic groups and educational backgrounds, you will randomly select 200 students from low-income families, 400 students from middle-income families, and 400 students from high-income families in each country. This is an example of a

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This is an example of a comparative study that uses random sampling to ensure representation from different socioeconomic groups and educational backgrounds in the samples. The study aims to compare mathematics knowledge among 15-year-olds in the US and Japan by administering a mathematics achievement test to 1000 students from each country.
Hi! I'd be happy to help with your question. You would like to compare mathematics knowledge among 15-year-olds in the US and Japan by giving a mathematics achievement test to samples of 1000 15-year-olds in each of the two countries, with 200 students from low-income families, 400 students from middle-income families, and 400 students from high-income families in each country. This is an example of a stratified random sampling method.

In this case, the population is divided into different strata based on socioeconomic groups (low-income, middle-income, and high-income families), and then random samples are drawn from each stratum. This ensures that the samples include individuals from all different socioeconomic groups and educational backgrounds, which allows for a more accurate comparison between the two countries.

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F varies directly as the cube root of G and
inversely as the square of H. The relation
between F, G and His F =cG^pH^q, where c is
a constant. State the value of p and q.

Answers

The value of p is 2/9 and q is -2 in the equation.

We have,

If F varies directly as the cube root of G and inversely as the square of H, we can write:

F ∝ [tex]G^{1/3} / H^2[/tex]

Using the constant of proportionality c, we can write:

[tex]F = c(G^{1/3} / H^2)[/tex]

To express F in terms of G and H only, we can raise both sides of the equation to the power of 3/2:

[tex]F^{3/2} = c~G(H^2)^{-3/2}\\F^{3/2} = c~G/H^3[/tex]

Now we can raise both sides of the equation to the power of 2/3:

[tex]F^{2/3} = (c~G/H^3)^{2/3}\\F^{2/3} = c^{2/3}G^{2/9}H^{-2}[/tex]

Therefore,

The value of p is 2/9 and q is -2.

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Suppose that scores on an exam are normally distributed with mean 80 and standard deviation 5, and that scores are not rounded. What is the probabilit

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The probability is approximately 0.9544 or 95.44%.

How that a randomly selected student scored between 70 and 90 on the exam?

To solve this problem, we need to calculate the z-scores for both values of interest and use a standard normal distribution table or calculator to find the probability.

The z-score for a score of 70 is:

z = (70 - 80) / 5 = -2

The z-score for a score of 90 is:

z = (90 - 80) / 5 = 2

Using a standard normal distribution table or calculator, we can find the probability that a randomly selected student scored between -2 and 2 on the standard normal distribution. This probability is approximately 0.9544.

However, we need to adjust this probability to account for the fact that the scores are not rounded. Since the distribution is continuous, we need to use the probability of the interval between 70 and 90, inclusive, which is:

P(70 ≤ X ≤ 90) = P(X ≤ 90) - P(X < 70)

where X is the random variable representing the exam score.

Using the z-scores we calculated earlier, we can find these probabilities as:

P(X ≤ 90) = P(Z ≤ 2) ≈ 0.9772

P(X < 70) = P(Z < -2) ≈ 0.0228

So, the probability of a randomly selected student scoring between 70 and 90 on the exam is:

P(70 ≤ X ≤ 90) = P(X ≤ 90) - P(X < 70) ≈ 0.9772 - 0.0228 = 0.9544

Therefore, the probability is approximately 0.9544 or 95.44%.

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Summarize the center of the data set below by determining the median. 20, 18, 26, 24, 32

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Answer:

18, 20, 24, 26, 32

The median is 24.

A student must answer five out of 10 questions on a test, including at least two of the first five questions. How many subsets of five questions can be answered

Answers

The total number of subsets of 5 questions that can be answered is 252 + 1 + 226 = 479.

To answer this question, we can use combinations. There are a total of 10 questions on the test, and we need to choose 5 out of them. However, we must ensure that we choose at least two questions from the first five.

To find the total number of subsets of 5 questions that can be answered, we can use the combination formula:

nCr = n! / (r! * (n-r)!)

where n is the total number of questions and r is the number of questions we need to choose (in this case, r=5).

So, we can calculate:

- The number of ways to choose any 5 questions out of 10: 10C5 = 252

- The number of ways to choose any 5 questions out of the last 5: 5C5 = 1

- The number of ways to choose 5 questions, including at least 2 from the first 5:

  - Choose 2 from the first 5, and 3 from the last 5: 5C2 * 5C3 = 100
  - Choose 3 from the first 5, and 2 from the last 5: 5C3 * 5C2 = 100
  - Choose 4 from the first 5, and 1 from the last 5: 5C4 * 5C1 = 25
  - Choose all 5 from the first 5: 5C5 = 1

  Total: 100 + 100 + 25 + 1 = 226

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Parametric models are reliable when the models are flexible in terms of the project's size. Group of answer choices True False

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It is false that Parametric models are reliable when the models are flexible in terms of the project's size

Parametric models are mathematical models that make assumptions about the distribution of the data being modeled. These models rely on the estimation of one or more parameters that define the distribution, such as the mean and variance of a normal distribution.

While parametric models can be very useful when the underlying assumptions are met and the data follows the assumed distribution, they can be unreliable when the assumptions are not met. For example, if the data does not follow a normal distribution, using a parametric model based on a normal distribution may lead to incorrect conclusions.

In terms of project size, the reliability of parametric models depends on the specific model and the nature of the data being modeled. Some parametric models may be more or less flexible in terms of accommodating different sample sizes or project sizes. However, in general, the reliability of a parametric model depends on the appropriateness of the underlying assumptions and the fit of the model to the data, rather than the size of the project.

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A rectangular pool is surrounded by a walk 4 feet wide. The pool is 6 feet longer than it is wide. The total area is 272 square. What are the dimensions of the pool

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The width of the pool is 18 feet, and the length is 24 feet (since it is 6 feet longer than the width).

Let's represent the width of the pool as x. Then, the length of the pool would be x + 6.

The total area of the pool and walk is given by:

Total area = (length + 2(4)) × (width + 2(4))

Total area = (x + 6 + 8) × (x + 4)

Total area = (x + 14) × (x + 4)

The area of the pool itself is given by:

Pool area = length × width

Pool area = x(x + 6)

Pool area = x² + 6x

We're told that the total area is 272 more than the area of the pool:

Total area = Pool area + 272

(x + 14) × (x + 4) = x² + 6x + 272

Expanding the left side of the equation:

x² + 18x + 56 = x² + 6x + 272

Simplifying the equation:

12x = 216

Solving for x:

x = 18

So the width of the pool is 18 feet, and the length is 24 feet (since it is 6 feet longer than the width).

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Full Question: A rectangular pool is surrounded by a walk 4 feet wide. The pool is six feet longer than its wide. If the total area is 272 ft² more than the area of the pool,what are the dimension of the pool?

Every day, the 15 students in Dr. Kelly's AP Chem class are randomly divided into 5 lab groups of 3 students each. What is the probability that three of the students - Anthony, Brian, and Chantal - are in the same lab group today

Answers

The probability that Anthony, Brian, and Chantal are in the same lab group today is approximately 0.8703, or about 87.03%.

There are 15 students in total, so there are 15 ways to choose the first student, 14 ways to choose the second student (since one has already been chosen), and 13 ways to choose the third student (since two have already been chosen). However, since the lab groups are identical, we need to divide by the number of ways to arrange the group of three students, which is 3! = 6. Therefore, the total number of ways to choose a group of three students is:

15 x 14 x 13

6

Simplifying this expression gives:

(15 x 14 x 13) / 6 = 455

There are 5 lab groups, and we want to find the probability that Anthony, Brian, and Chantal are all in the same group. There are 3 ways to choose which group they will be in, and then we need to choose 2 more students to join them, which can be done in:

12 x 11

2

ways, since there are 12 students remaining to choose from after we have chosen Anthony, Brian, and Chantal, and we need to choose 2 more students to join them. Therefore, the total number of ways that Anthony, Brian, and Chantal can be in the same group is:

3 x (12 x 11) = 396

Finally, we can calculate the probability by dividing the number of favorable outcomes (i.e., Anthony, Brian, and Chantal are in the same group) by the total number of possible outcomes:

P(Anthony, Brian, Chantal in same group) = 396 / 455

≈ 0.8703

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If the correlation between two variables was equal to 0, the scatterplot between these two variables would be represented as

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If the correlation between two variables was equal to 0, the scatterplot between these two variables would be represented as a graphical representation of the relationship between two variables

If the correlation between two variables is equal to 0, it means that there is no linear relationship between the two variables. In other words, as one variable changes, the other variable does not systematically change in any particular direction.

In a scatterplot, which is a graphical representation of the relationship between two variables, this would be represented by a random scattering of data points with no discernible pattern or trend. The points would be evenly distributed throughout the plot, without any apparent clustering in one direction or another.

Additionally, the line of best fit, which is used to describe the overall trend of the data, would be a horizontal line with a slope of zero, indicating that there is no relationship between the two variables.

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