Question

Sally test grades in English and 75 and 80 what grade must she get on her next test so the average is in 85?

Answer 1

Explanation

We are told that Sally scored 75 and 80 on two English tests

We are then asked to determine the next grade she must have so that the average becomes 85

Thus

let the third grade be x

Hence

The total grades of the three tests will be

$75+80+x$

The average of the three tests will be

$\frac{75+80+x}{3}$

Since the average is 85, then we will have

$\frac{75+80+x}{3}=85$

We can now solve for x

$\begin{gathered} 75+80+x=3\times85 \\ 155+x=255 \\ x=255-155 \\ x=100 \end{gathered}$

Thus, she must score 100 on her third test