35Mean of five scores

The mean of five test scores is 82. Four of the scores are 78, 85, 90 and 74. Find the fifth score.

The fifth score is 83. Five scores averaging 82 must total 410; the four given scores add to 327, so 410 − 327 = 83. Check: 78+85+90+74+83 = 410, and 410/5 = 82.