Question

Ravi has scored 99, 61, 71, and 83 on his previous four tests. What score does he need on his next test so that his average (mean) is 78?

Answer 1

59

Explanation:

Let s = score needed on the next test

(99 + 71 + 83 + s)/4 = 78

Multiply both sides by 4 to remove the fraction.

(4)(99 + 71 + 83 + s)/4 = 78(4)

99 + 71 + 83 + s = 312

253 + s = 312

s = 312 - 253

s = 59