The ulna is a bone found in the forearm of humans. The length of the ulna is approximately normal.

To estimate the population mean length for male adults, 19 male adults are randomly selected. The sample mean of ulna length was 25.2 cm and the standard deviation was 1.1 cm.

1a. Calculate a 95% confidence interval for the population mean.

1b. Interpret a 95% confidence interval for the population mean.

2. For the prior question, you calculated a 95% confidence for the population mean length of the ulna for males.

a. If you changed the confidence level to 99%, what would happen to the margin of error? The margin of error would (increase/decrease/stay the same).

b. If you changed the sample size to 25, what would happen to the margin of error?

The margin of error would (increase/decrease/stay the same).