I need help please

The first-serve percentage of a tennis player in a match is normally distributed with a standard deviation of 4.3%. if a sample of 15 random matches of the player is taken, the mean first-serve percentage is found to be 26.4%. what is the margin of error of the sample mean? a. 0.086% b. 0.533% c. 1.11% d. 2.22%

Afootball is throw by a quarterback to a receiver

Olga bought a new skirt that cost $20. sales tax is 5%. how much did olga pay, including sales tax? 7.