Plz help! Giving a lot of points! :)

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%

You have 138.72 in your saving account u take out 45.23 and 18.00 you deposit 75.85 into your account

Interpret the following expression (5y^2-7)^3/(2y)^2