Question

In 2010, an online security firm estimated that 65% of computer users don't change their passwords very often. Because this estimate may be outdated, suppose that you want to carry out a new survey to estimate the proportion of students at your school who do not change their password. You would like to determine the sample size required to estimate this proportion with a margin of error of 0.05.

(a)

Using 0.65 as a preliminary estimate, what is the required sample size if you want to estimate this proportion with a margin of error of 0.05? (Round your answer up to the nearest integer.)

(b)

How does the sample size in part (a) compare to the sample size that would result from using the conservative value of 0.5? (Round your answer up to the nearest integer.)

The sample size in part (a) [[is smaller than]] the sample size of ___??___computed using the conservative estimate.

(c)

What sample size would you recommend? Justify your answer. (Round your sample size up to the nearest integer.)

The sample size of __??___  should be used for this study because it will guarantee a margin of error of no greater than 0.05. The other sample size computed will only guarantee a margin of error no greater than 0.05 if p > __??__ or if p < __??__

Answer 1

Assuming that confidence level is 95%.

(a)

(b)

(c)

The sample size of 385 should be used for this study because it will guarantee a margin of error of no greater than 0.05. The other sample size computed will only guarantee a margin of error no greater than 0.05 if p  < 0.65.