Question

what number does someone need on the next test to keep the 81 mean if the past 3 tests had
59, 87, 97

Answer 1

81,

First, reverse the mean equation of sum of all #’s divided by the # of #’s to the mean times the # of #’s to get the sum of all numbers.

81*4=324

Then we subtract the sum of the three #’s.

324-243=81