3. Interval estimation - The role of sample size in confidenceintervals

Suppose you are interested in the proportion of child safety seats located in a particular warehouse that are defective. You randomly select a sample of child safety seats from the population of child safety seats in that warehouse. The sample provides a sample proportion of 0.31. You construct a 95% confidence interval for the proportion of child safety seats that are defective.

If the number of child safety seats in the sample is 100, then the confidence interval is .

If the number of child safety seats in the sample is 250, then the confidence interval is .

As the sample size increases, the confidence interval .

Suppose you would like to have a confidence interval that is about 0.028 wide. What sample size do you need to achieve that 0.028? (Note:Select the sample size that most closely matches the desired interval width.)

500

1,000

250

5,000