compute the power of the test if the researcher uses a sample of n=16 individuals ...

A researcher is evaluating the influence of a treatment using a sample selected from a normally distributed population with a mean of u=80 and a standard deviation of 0=20. The researcher expects a 12-point treatment effect and plans to use a two-tailed hypothesis test with a=.05.
a. compute the power of the test if the researcher uses a sample of n=16 individuals
b. compare the power of the test if the researcher uses a sample of n=25 individuals