All changes save 10. Abby scored 92, 88, 86, 88, and 71 on five math tests. Which method below could Abby use to calculate the mean for her test scores?
a. subtract the least value from the greatest
b. choose the test score that repeats itself the most
c. add her test scores and divide the sum by 5
d. order her test scores from least to greatest and choose the score in the middle