Igot stuck again. i don't understand how to figure out this answer.

In trapezoid klmn, kj=19.2 and jm=22.5. identify ln.

A. 127 cm^2 b. 144.5 cm^2 c. 172 cm^2 d. 50 cm^2

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%