(Solved) Math225 Week 6 Assignment: Estimating Sample Size for a Population Proportion

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.

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 be 92% confident that the estimated (sample) proportion is within 3 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.

Question

Suppose a shoe store wants to determine the current percentage of customers who are males. How many customers should the company survey in order to be 98% confident that the estimated (sample) proportion is within 3 percentage points of the true population proportion of customers who are males?

 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.

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.

Solution:

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.