Please help me ASAP! i need help, i’d really appreciate it:)

You can find the constant of proportionality by finding the ratio of

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%

Either enter an exact answer in terms of \piπ or use 3.143.14 for \piπ and enter your answer as a decimal.