Which value must be added to the expression x^2+12x to make it a perfect square trinomial

"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

4 years ago

5/8x - 11/2 = 3/4 <br> what does the x equal ?

Verizon [17]

Answer:

x=10

Step-by-step explanation:

5/8x - 11/2 = 3/4

Multiply each side by 8 to clear the fractions

8(5/8x - 11/2 = 3/4)

5x - 44 = 6

Add 44 to each side

5x-44+4= 6+4

5x= 50

Divide by 5

5x/5 = 50/5

x =10

6 0

3 years ago

To illustrate the effects of driving under the influence of alcohol, a police officer brought a DUI simulator to a local high sc

nexus9112 [7]

Answer:

Check the explanation

Step-by-step explanation:

Here we have to first of all carry out dependent sample t test. consequently wore goggles first was selected at random for the reason that the reaction time in an emergency taken with goggles would be greater than the amount of reaction time in an emergency taken with not so weakened vision. So that we will get the positive differences d = impaired - normal

b)

To find 95% confidence interval first we need to find sample mean and sample sd for difference d = impaired minus normal.

We can find it using excel that is in the first attached image below,

Therefore sample mean $( \bar{X}_{d} )$ = 0.98

Sample sd $( \bar{S}_{d} )$ = 0.3788

To find 95% Confidence interval we can use TI-84 calculator,

Press STAT ----> Scroll to TESTS ---- > Scroll down to 8: T Interval and hit enter.

Kindly check the attached image below.

Therefore we are 95% confident that mean difference in braking time with impaired vision and normal vision is between ( 0.6888 , 1.2712)

Conclusion : As both values in the interval are greater than 0 , mean difference impaired minus normal is not equal to 0

There is significant evidence that there is a difference in braking time with impaired vision and normal vision at 95% confidence level .

7 0

3 years ago

The perimeter of a rectangle downtown courtyard is 174 feet. The width of the rectangle is twice the length. Find the length and

kirill [66]

Answer:

Step-by-step explanation:

L = Length

W = Width

W = 2L

2W + 2L = 174

2(2L) + 2L = 174

6L = 174

L = 29 ft

W = 2(29) = 58 ft

5 0

3 years ago

How do you show your work of 47 divided by 6?

saw5 [17]

Answer:

this is how you do it .

it doesn't have a end it just kept going

7 0

3 years ago