Damon has taken six history tests so far this year. The tests are out of twenty-five points, and he has gotten the following scores.

21, 20, 24, 19, 20, 24

What must Damon score on his seventh test in order to have a mean of 21?

19
20
21
22

Question

Damon has taken six history tests so far this year. The tests are out of twenty-five points, and he has gotten the following scores.

21, 20, 24, 19, 20, 24

What must Damon score on his seventh test in order to have a mean of 21?

19
20
21
22

Mercury · Answer

old question, answering to close

mean = (sum of values) / (# of values)

let's suppose the seventh test is x. the sum of scores is therefore 21 + 20 + 24 + 19 + 20 + 24 + x

# of values is 7 since there are 7 total tests

mean is 21

plug in the appropriate quantities and solve for x