Help please!!!!!!!!!!!!!!

"A cable TV company wants to estimate the percentage of cable boxes in use during an evening hour. An approximation is 20 percen

Marizza181 [45]

Answer:

The company should take a sample of 148 boxes.

Step-by-step explanation:

Hello!

The cable TV company whats to know what sample size to take to estimate the proportion/percentage of cable boxes in use during an evening hour.

They estimated a "pilot" proportion of p'=0.20

And using a 90% confidence level the CI should have a margin of error of 2% (0.02).

The CI for the population proportion is made using an approximation of the standard normal distribution, and its structure is "point estimation" ± "margin of error"

[p' ± $Z_{1-\alpha /2} * \sqrt{\frac{p'(1-p')}{n} }$ ]

Where

p' is the sample proportion/point estimator of the population proportion

$Z_{1-\alpha /2} * \sqrt{\frac{p'(1-p')}{n} }$ is the margin of error (d) of the confidence interval.

$Z_{1-\alpha /2} = Z_{1-0.05} = Z_{0.95}= 1.648$

So

$d= Z_{1-\alpha /2} * \sqrt{\frac{p'(1-p')}{n} }$

$d *Z_{1-\alpha /2}= \sqrt{\frac{p'(1-p')}{n} }$

$(d*Z_{1-\alpha /2})^2= \frac{p'(1-p')}{n}$

$n*(d*Z_{1-\alpha /2})^2= p'(1-p')$

$n= \frac{p'(1-p')}{(d*Z_{1-\alpha /2})^2}$

$n= \frac{0.2(1-0.2)}{(0.02*1.648)^2}$

n= 147.28 ≅ 148 boxes.

I hope it helps!

3 0

3 years ago

Select all the stories that can be represented by the diagram.

Inessa05 [86]

Answer: Choice C and Choice D

========================================================

Explanation:

Choice A doesn't work because it the $1 should be $7 instead.
Choice B doesn't work because it should be Elena spending $7 total on 3 notebooks and a $1 pen. The x is the amount per notebook.
Choice C does work. If x is the number of grapes Noah gives each friend, then 3x is the total amount Noah gives over. Then 3x+1 is the number of grapes total. That +1 at the end is the grape Noah eats. We end up with 3x+1 = 7 because Noah starts off with 7 grapes.
Choice D works also. The x is the number of hours for math, science and history each. So 3x is the combined time of those three classes. Add on 1 to get 3x+1 to represent all 7 hours, ie 3x+1 = 7.
Choice E does not work. If it was her spending $7 on 3 markers and a $1 pen, then it would work.

8 0

2 years ago

Read 2 more answers

The sum of two numbers is eighteen. The total of three times the smaller and twice the larger is forty-four. Find the two number

sashaice [31]

Answer:

The numbers are 8 and 10.

Step-by-step explanation:

Let the numbers be x and y.

The sum of two numbers is eighteen:

x + y = 18

The total of three times the smaller and twice the larger is forty-four:

3x + 2y = 44

Solve the system by substitution:

x = 18 - y

Substitute x and solve for y:

3(18 - y) + 2y = 44
54- 3y + 2y = 44
54 - y = 44
y = 54 - 44
y = 10

Find x:

x = 18 - 10
x = 8

6 0

2 years ago

Write the equation for this line in y=blanks+blank<br><br> **Please see picture**

Diano4ka-milaya [45]

Equation for this line is y = -2x + (-4)

<u>Step-by-step explanation:</u>

Step 1:

Slope intercept equation for a line is of the form y= mx + b, where m is the slope and b is the y-intercept.

Step 2:

Calculate slope of the given line.

⇒ m = (y2 - y1)/(x2 - x1) = (2 - (-2))/(-3 - (-1)

⇒ m = 4/-2 = -2

Step 3:

Find y-intercept

⇒ b = - 4

Step 4:

Substitute values to get equation

⇒ y = -x -4 or y = - (x + 4)

5 0

3 years ago

Emily buys 240 square feet of carpet. She can convert square feet to square yards by dividing the number of square feet by 9. Ho

alex41 [277]

Answer:

26.66667 yards of carpet (240/9)

Step-by-step explanation:

6 0

3 years ago