Answer:
5
Step-by-step explanation:
x² - 4x = 5
x² - 4x - 5 = 0
the solution of a quadratic equation is
x = (-b ± sqrt(b² - 4ac))/(2a)
a = 1
b = -4
c = -5
x = (4 ± sqrt(16 + 20))/2 = (4 ± sqrt(36))/2
x1 = (4 + 6)/2 = 5
x2 = (4 - 6)/2 = -1
since we are looking only for a positive number, x=5 is the answer.
A display case of disposable tablecloths are marked 5 for $3. If Peter has $21, how many plastic tablecloths can Peter get?
Answer:
35
Step-by-step explanation:
3x7=35
There are 60 students and 13 teachers on a bus .what is the ratio of students to teachers.
Please help ASAP!!! Thank you!!!
For each one of the following statements, indicate whether it is true or false.
(a) If X = Y (i.e., the two random variables always take the same values), then Van X | Y = 0.
(b) If X = Y (the two random variables always take the same values), then Var (X | Y) = Var (X).
(c) If Y takes on the value y, then the random variable Var (X | Y) takes the value E[(X – E[X | Y = y])2 |Y = y].
(d) If Y takes on the value y, then the random variable Var (X | Y) takes the value E[(X - E[X | Y])2 | Y = y].
(e) If Y takes on the value y, then the random variable Var ( X | Y) takes the value E[(X – E[X])2 | Y = y].
Solution :
a). [tex]$\text{Var} (X|Y) =E ((X-E(X|Y))^2 |Y)$[/tex]
Now, if X = Y, then :
[tex]P(X|Y)=\left\{\begin{matrix} 1,& \text{if } x=y \\ 0, & \text{otherwise }\end{matrix}\right.[/tex]
Then, E[X|Y] = x = y
So, [tex]$\text{Var} (X|Y) =E((X-X)^2 |Y)$[/tex]
[tex]$=E(0|Y)$[/tex]
= 0
Therefore, this statement is TRUE.
b). If X = Y , then Var (X) = Var (Y)
And as Var (X|Y) = 0, so Var (X|Y) ≠ Var (X), except when all the elements of Y are same.
So this statement is FALSE.
c). As defined earlier,
[tex]$\text{Var} (X|Y) =E ((X-E(X|Y))^2 |Y=y)$[/tex]
So, this statement is also TRUE.
d). The statement is TRUE because [tex]$\text{Var} (X|Y) =E ((X-E(X|Y))^2 |Y=y)$[/tex].
e). FALSE
Because, [tex]$\text{Var} (X|Y) =E ((X-E(X|Y=y))^2 |Y=y)$[/tex]
In an examination every student took history or geography or both of 500 candidates 60% took history whiles 72% took geography. How many students took both subjects
Answer:
80 students
Step-by-step explanation:
Answer:
80
Step-by-step explanation:
60% of 500 = 300
72% of 500 = 360
40% of 500 = 200
28% of 500 = 140
300+360 = 660
660 - 2x = 500
660 - 500 = 2x
160 = 2x
2x = 160
x = 80
Question 2
A force F=5i+3j-2k is applied to move a block of cement from A(0,1,1) to B(4.-1,3).
Determine the work done by the force.
The work is simply the dot product of the force and displacement (which I assume are given in Newtons and meters, respectively):
W = F • d
W = (5i + 3j - 2k) N • ((4i - j + 3k) m - (j + k) m)
W = (5i + 3j - 2k) • (4i - 2j + 2k) Nm
W = (20 - 6 - 4) Nm
W = 10 J
The mean of 19 numbers is 1600. If 2000 is added in the number. Find the new mean
Answer:
Here's your answer .
hope it helps you
An expression to convert 50 miles per hour to miles per minute is shown.
What value can be entered in the box to correctly make this conversion?
Answer:
[tex]{ \tt{ = \frac{50}{1 \times 60} }}[/tex]
Step-by-step explanation:
50 miles=50 miles
1 hour=60 minutes
50÷60
0.8333333333333333mile per minute
~1.0 mile per minute
Plz help I’ll mark you
Answer:
The option B, c2=a2+b2−2ab• cos(B) is the right answer.
HELPPP PLEASEEE! I tried everything from adding to dividing, subtracting, multiplying but still no correct answer. Can someone help me out here please? I am not sure where to start either now. Thank you for your time.
You have some data points labeled by [tex]x[/tex]. They form the set {3, 5, 7}.
The mean, [tex]\bar x[/tex], is the average of these values:
[tex]\bar x = \dfrac{3+5+7}3 = \dfrac{15}3 = 5[/tex]
Then in the column labeled [tex]x-\bar x[/tex], what you're doing is computing the difference between each data point [tex]x[/tex] and the mean [tex]\bar x[/tex]:
[tex]x=3 \implies x-\bar x = 3 - 5 = -2[/tex]
[tex]x=5 \implies x-\bar x = 5-5 = 0[/tex]
[tex]x=7 \implies x-\bar x = 7 - 5 = 2[/tex]
These are sometimes called "residuals".
In the next column, you square these values:
[tex]x=3 \implies (x-\bar x)^2 = (-2)^2 = 4[/tex]
[tex]x=5 \implies (x-\bar x)^2 = 0^2 = 0[/tex]
[tex]x=7 \implies (x-\bar x)^2 = 2^2 = 4[/tex]
and the variance of the data is the sum of these so-called "squared residuals".
Suppose X and Y are two independent exponential variables. The mean of X is twice the mean of Y. If the probability of X exceeding 50 is 0.7788, what is the probability of Y exceeding 40
If X ~ Exponential(µ), then the mean of X is 1/µ. So if the mean of X is twice the mean of Y, then the mean of Y is 1/(2µ), so that Y ~ Exponential(2µ).
We're given that
P(X > 50) = 1 - P(X ≤ 50) = 1 - Fx (50) ≈ 0.7788
==> Fx (50) = P(X ≤ 50) ≈ 0.2212
where Fx is the CDF of X, which is given for 0 ≤ x < ∞ to be
Fx (x) = 1 - exp(-µx)
Solve for µ :
1 - exp(-50µ) ≈ 0.2212 ==> µ ≈ -ln(0.7788)/50 ≈ 0.005
Then we have
P (Y > 40) = 1 - P (Y ≤ 40) = 1 - Fy (40)
where Fy is the CDF of Y,
Fy (y) = 1 - exp(-2µy)
so that
P (Y > 40) ≈ 1 - exp(-2 × 0.005 × 40) ≈ 0.3297
(a) The heights of male students in a college are thought to be normally distributed with mean 170 cm and standard deviation 7.
The heights of 5 male students from this college are measured and the sample mean was 174 cm.
Determine, at 5% level of significance, whether there is evidence that the mean height of the male students of this college is higher than 170 cm.
[6]
(b) (i) The result of a fitness trial is a random variable X which is normally distributed with mean μ and standard deviation 2.4 . A researcher uses the results from a random sample of 90 trials to calculate a
98% confidence interval for μ . What is the width of this interval?
[4]
(ii) Packets of fish food have weights that are distributed with standard deviation 2.3 g. A random sample of 200 packets is taken. The mean weight of this sample is found to be 99.2 g. Calculate a 99% confidence interval for the population mean weight.
[4]
(c) (i) Explain the difference between a point estimate and an interval
Estimate. [2]
(ii) The daily takings, $ x, for a shop were noted on 30 randomly chosen days. The takings are summarized by Σ x=31 500 and
Σ x2=33 141 816 .
Calculate unbiased estimates of the population mean and variance of the shop’s daily taking. [4
Answer:
the answer is 50 but I don't know if
a plant grows by 1.67cm in its first week. each week it grows by 4% more than it did the week before. by how much will grow in nine weeks, including the first week?
Answer: Approximately 2.29 cm
Step-by-step explanation:
Week 1 = 1.67 or [tex]1.67(1.04)^{0}[/tex]Week 2 = 1.67 + (1.67 · 4%) = 1.67 + 1.67 · 0.04 = 1.67(1 + 0.04) = 1.67(1.04)¹Week 3 = 1.67(1.04) + [1.67(1.04) · 0.04] = 1.67(1.04)(1.04) = 1.67(1.04)² Week 4 = 1.67(1.04)² + [1.67(1.04)² · 0.04] = 1.67(1.04)²(1.04) = 1.67(1.04)³See a pattern?
Number of week = xPlant growth = [tex]1.67(1.04)^{x-1}[/tex]Week 9 = [tex]1.67(1.04)^{9-1} =1.67(1.04)^{8} =1.67(1.3686)=2.2855[/tex]
Which of the following is the minimum value of the equation y = 2x2 + 5?
5
0
−5
2
B
13 ft.
5 ft.
A
C
12 ft.
Find the value of Cos (B) =
Answer: the answer is 12/13
4g+r=2r-2x
I need someone’s help if you can help me
Answer:
4g+2x=r
Step-by-step explanation:
4g+r=2r-2x
collecting like terms
4g+2x=2r-r
4g+2x=r
You and Michael have a total of $19.75. If Michael has $8.25, how much
money do you have?
$27.00
$28.00
$11.50
$12.00
Answer:
You have a total of $11.50
Step-by-step explanation:
We first subtract $19.75 by $8.25 and the result will be $11.50
Answer:
11.50
Step-by-step explanation:
19.75-8.35= 11.50
May I have the brainiest?
Use Lagrange multipliers to solve the following exercise. A home improvement contractor is painting the walls and ceiling of a rectangular room. The volume of the room is 18042.75 cubic ft. The cost of wall paint is $0.06 per square foot and the cost of ceiling paint is $0.11 per square foot. Find the room dimensions that result in a minimum cost for the paint.
Answer:
Let the width of the garden =x meter
Then length=(x+4) meter
Half perimeter =36 m
So perimeter of garden =(2×36)=72 meters
According to the question
⇒2(l+b)=72
⇒2(x+x+4)=72
⇒2x+2x+4=74⇒4x=64⇒x=16 meters
Hence,the width of the garden =16 meters
The length of the garden =(16+4)=20 meters
What is the domain of the given
set of ordered pairs?
(2, 4), (5,5), (8, 6), (11, 7)
Answer:
2, 5, 8, 11
Step-by-step explanation:
The domian is the x axis points thingy
Please answer this question -+ is equals to what
Answer:
It means that there are two answers, a positive one and a negative one.
Step-by-step explanation:
If you get +-5, then you have two answers: +5 and -5
for the equation (x+3)(x+1)=1 explain why the solutions are not -3 and -1
Answer:
Step-by-step explanation:
(x+3)(x+1)=1
x²+3x+x+3=1
x²+4x+2=0
x²+4x+4=-2+4
(x+2)²=2
x+2=±√2
x=2+√2
and x=2-√2
so x≠-3
and x≠-1
If P = (2,-1), find the image
of P under the following rotation.
270° counterclockwise about the origin
([?], [])
Enter the number that belongs in
the green box.
9514 1404 393
Answer:
P'(-1, -2)
Step-by-step explanation:
The transformation for 270° CCW rotation is ...
(x, y) ⇒ (y, -x)
Then the image of the given point is ...
P(2, -1) ⇒ P'(-1, -2)
Given the function
Calculate the following values:
Answer:
f(-1) = 1
f(0) = 20
f(2) = 38
Step-by-step explanation:
f(-1) = 9×-1 + 10 = -9 + 10 = 1
f(0) = 9×0 + 20 = 0 + 20 = 20
f(2) = 9×2 + 20 = 18 + 20 = 38
we needed to use the second definition for f(0), because that is the same as saying x=0.
and that is in the domain of the second function definition ( x>=0).
what is the difference between dot product and cross product?
Answer:
A dot product is the product of the magnitude of the vectors and the cos of the angle between them. A cross product is the product of the magnitude of the vectors and the sine of the angle that they subtend on each other.
Step-by-step explanation:
The diameters of bolts produced in a machine shop are normally distributed with a mean of 5.7 millimeters and a standard deviation of 0.08 millimeters. Find the two diameters that separate the top 3% and the bottom 3%. These diameters could serve as limits used to identify which bolts should be rejected. Round your answer to the nearest hundredth, if necessary.
Answer:
The diameter that separates the top 3% is of 5.85 millimeters, and the one which separates the bottom 3% is of 5.55 millimeters.
Step-by-step explanation:
Normal Probability Distribution:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the z-score of a measure X is given by:
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.
Mean of 5.7 millimeters and a standard deviation of 0.08 millimeters.
This means that [tex]\mu = 5.7, \sigma = 0.08[/tex]
Top 3%
The 100 - 3 = 97th percentile, which is X when Z has a p-value of 0.97, so X when Z = 1.88.
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
[tex]1.88 = \frac{X - 5.7}{0.08}[/tex]
[tex]X - 5.7 = 1.88*0.08[/tex]
[tex]X = 5.85[/tex]
Bottom 3%
The 3rd percentile, which is X when Z has a p-value of 0.03, so X when Z = -1.88.
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
[tex]-1.88 = \frac{X - 5.7}{0.08}[/tex]
[tex]X - 5.7 = -1.88*0.08[/tex]
[tex]X = 5.55[/tex]
The diameter that separates the top 3% is of 5.85 millimeters, and the one which separates the bottom 3% is of 5.55 millimeters.
2. Find the Perimeter AND Area of the
figure below.
5 in.
6 in.
8 in.
9 in.
Helppppppppp ASAP!!!!!
The graphs below have the same shape . The equation of the blue graph is f(x) =2^x . Which of these is the equation of the red graph
Answer:
[tex]{ \bf{c). \: g(x) = {2}^{x} - 2 }}[/tex]
3p + 2q = 14
10p + 6q = 44
What is p and what is q
Answer:
p = 2 ; q = 4
Step-by-step explanation:
Given tbe equation :
3p + 2q = 14 - - - (1)
10p + 6q = 44 - - -(2)
What is p and what is q
This is a simultaneous equation ; using elimination method :
Multiply (1) by 6 and (2) by 2
18p + 12q = 84 - - - - (3)
20p + 12q = 88 - - - (4)
Subtract (3) and (4)
-2p = - 4
p = 4/2
p = 2
Put p = 2 in (1)
3p + 2q = 14
3(2) + 2q = 14
6 + 2q = 14
2q = 14 - 6
2q = 8
q = 8/2
q = 4
p = 2 ; q = 4
Using the graph below, if f(x) = 4, find x.
find the value of the following 425×167+233×425 step by step explanation
Answer:
so first we start from the left
425*167=70975
but instead of adding this to 233 we use pemdas so instead we do
233*425=99025
now we add them together
70975+99025=170000
Hope This Helps!!!
Answer:
170,000
Step-by-step explanation:
425 × 167 + 233 × 425
= (425 × 167) + (233 × 425)
= 70,975 + 99,025
= 170,000
Thinking Critically and Solving Problems
About how much did the percent of working women with some college or an associate degree change
from 1996 to 2016?
Use the graph to answer the question.
Percent of women in the labor
force by educational attainment
100%
OOOO
A) 0%
B) 8%
C) 12%
D) 70%
80%
60%
Less than a high school diploma
High school graduates, no college
Some college or associate degree
Bachelor's degree and higher
40%
20%
0%
SUBMIT
1996
2006
2016
Source: U.S. Bureau of Labor Statistics
Question 16 of 21
31 AM
Answer:maybe B?
Step-by-step explanation: