Assume that the sample is a simple random sample obtained from a normally distributed population of IQ scores of statistics professors. Use the table below to find the minimum sample size needed to be 99% confident that the sample standard deviation s is within 50%of . Is this sample sizepractical?

sigma

To be95% confident that s is within

1%

5%

10%

20%

30%

40%

50%

of the value of sigma

, the sample size n should be at least

19,205

768

192

48

21

12

8

To be99% confident that s is within

1%

5%

10%

20%

30%

40%

50%

of the value of sigma

, the sample size n should be at least

33,218

1,336

336

85

38

22

14