What is the answer to this question?

How can the correlation in the scatter plot graph below best be described? positive correlation negative correlation both positive and negative no correlation

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%

How is the interquartile range calculated?