# Week 6 Assignment: Estimating Sample Size for a Population Proportion

Calculate the sample
size required to estimate a population proportion with a given confidence level

Question

Suppose a clothing store wants to determine
the current percentage of customers who are over the age of forty. How many
customers should the company survey in order to be92% confident that the estimated (sample)
proportion is within5 percentage
points of the true population proportion of customers who are over the age of forty?

 z0.16 z0.08 z0.04 z0.02 z0.01 0.994 1.405 1.751 2.054 2.326

Use the table of values above.

Yes that’s right. Keep it up!

307

91

198

77

614

Calculate the sample size required to estimate a population
proportion with a given confidence level

## Question

Suppose an automotive repair company wants to determine the
current percentage of customers who keep up with regular vehicle maintenance.
How many customers should the company survey in order to be 90% confident
that the estimated (sample) proportion is within 2 percentage
points of the true population proportion of customers who keep up with regular
vehicle maintenance?

 z0.10 z0.05 z0.025 z0.01 z0.005 1.282 1.645 1.960 2.326 2.576

Use the table of values above.

423

609

1,028

1,692

3,383

Calculate the sample size required to estimate a population
proportion with a given confidence level

## Question

Suppose
an automotive repair company wants to determine the current percentage of
customers who keep up with regular vehicle maintenance. How many customers
should the company survey in order to be 95% confident that
the estimated (sample) proportion is within 2 percentage
points of the true population proportion of customers who keep up with regular
vehicle maintenance?

 z0.10 z0.05 z0.025 z0.01 z0.005 1.282 1.645 1.960 2.326 2.576

Use the table of values above.

322

601

1,692

2,401

9,604

Calculate the sample size required to estimate a population
proportion with a given confidence level

## Question

Virginia
wants to estimate the percentage of students who live more than three miles
from the school. She wants to create a 95% confidence
interval which has an error bound of at most 5%. How many students
should be polled to create the confidence interval?

 z0.10 z0.05 z0.025 z0.01 z0.005 1.282 1.645 1.960 2.326 2.576

Use the table of values above.

52

73

97

271

385