Answer:
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
She needs a grade of 71 on her next text.