Twenty percent of the town's population is over the age of 65. If there are 320 residents over the age of 65, what is the town's total population?

Given the following statements, which is the best

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%

Is this a polynomial function? i need to know asap