Kevin recorded the ages of the next 12 people who entered his grocery store. he asked his brother john to find the mean, median, and the mode of the data set: [ 6,18,8,4,18,20,10,10,21,6,17,18]. john's results are shown. mean =156/12=13. median = 20+10/2=15, mode=10.

a. determine whether john's answers are correct. if an answer is incorrect, explain his error and provide the correct response. show your work.

b. the data set was expanded to include the ages of the next three people who entered the store: 10, 12, and 52. compare the new measures of center to those in part (a), show your work.

c. determine the best measure of center for each data set. justify your answer