Question

Tammy has scored 82, 78, and 93 on her previous three tests. What score does she need on her next test so that her average (mean) is 81?

Answer 1

She needs a grade of 71 on her next text.

Explanation:

Mean of a data-set:

The mean of a data-set is the sum of all values in the data-set divided by the number of values.

Tammy has scored 82, 78, and 93 on her previous three tests.

Thus, her grades are 82, 78, 93 and x, in which x is her grade in the fourth test.

There are 4 tests.

What score does she need on her next test so that her average (mean) is 81?

We have to find x when the mean is 81. So

`(82 + 78 + 93 + x)/(4) = 81`

`253 + x = 324`

`x = 324 - 253`

`x = 71`

She needs a grade of 71 on her next text.