Question

Samuel made a list of his test scores: 88, 100, 92, 80, 85, 94, and 90. What is the lowest test score he can get on his next test to have mean score of 90?

Answer 1

he needs to get a 91 to have a mean score of 90

Explanation:

add up all the known scores to get 629

let 's' = lowest test score

(629 + s) ÷ 8 = 90 [we divide by 8 because there are 7 known and 1 unknown score)

cross-multiply to get:

629 + s = 720

s = 720-629

s = 91