Question

Chang has scored 73, 79, 72, 59, and 66 on his previous five tests. what score does he need on his next test so that her average (mean) is 73?

Answer 1

She needs 89 on her last test so that her mean is 73.

Explanation:

The mean is the sum of all test scores divided by the number of tests. So

`M = (S)/(T)`

In which M is the mean, S is the sum of the scores and T is the number of tests.

In this problem, we have that:

There are going to be 6 tests, the five previous and the last one. So
`T = 6`

We want an average of 73 for Chang. So
`M = 73`

Her scores are: 73, 79, 72, 59, 66 and x, in which x is her score on the next text. So
`S = 73 + 79 + 72 + 59 + 66 + x = 349 + x`

So

`M = (S)/(T)`

`73 = (349 + x)/(6)`

`349 + x = 73*6`

`x = 89`

She needs 89 on her last test so that her mean is 73.