Can someone me with this problems (:

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%

Do,h = (7, 9) (14, 18) the scale factor is

Solve for x where 0 equation: cot^2x+2cotx+1=0