Question: (4 points) Each of the following statements describes a change that might occur in a study, each of which may have an implication for sample size requirements, and something the researcher would need to address. Please choose the answer (a, b or c) the best reflects what the researcher should do for each of the instances described below.

a. Increase the sample size

b. Decrease the sample size

c. Need not change the sample size

The difference between the null and alternative means increases from 20 to 30.

A 90% confidence interval is chosen instead of a 95% confidence interval.

The population standard deviation is 20 instead of 10.

The null and alternative means both increase by 50.