Hello, I am having troubles figuring out how to solve this and the correct Excel formulas to get the right answers. Can you please explain how to solve that and the Excel formulas you used for it? :

Remark: For the problems below state precisely your null and alternative hypotheses in terms of your parameter and state your final conclusion about rejecting or not your null hypothesis.

Jeffrey is as an eight-year old, who used to believe that his mean time for swimming the 25-yard freestyle was 16.43 seconds. Jeffrey's dad, Frank, thought that Jeffrey could swim the 25-yard freestyle faster using goggles. Frank bought Jeffrey a new pair of expensive goggles and timed Jeffrey for 15 25-yard freestyle swims. For the 15 swims, Jeffrey's mean time was 16 seconds with a standard deviation of 0.8 seconds. Frank thought that the goggles helped Jeffrey to swim faster than the 16.43 seconds.

a) Conduct a hypothesis test using = 0.05. Assume that the swim times for the 25-yard freestyle are normal.

b) Conduct a hypothesis test using = 0.01. Assume that the swim times for the 25-yard freestyle are normal.