Question

Juwan has a third quiz in math on Friday. His two previous quiz grades were 85 and 72. What must he make on the third quiz for his quiz average to be at least an 88?

Answer 1

`x = 107`

Explanation:

Given

`Scores = 85\ and\ 72`

`Average = 88`

Required

Determine the third score

Average is calculated using;

`Average = (\sum x)/(n)`

In this case:

`n = 3`

`Average = (\sum x)/(n)`

Let the third score be x; So:

`Average = (85 + 72 + x)/(3)`

Substitute 88 for Average

`88 = (85 + 72 + x)/(3)`

`88 = (157 + x)/(3)`

Multiply through by 3

`3 * 88 = (157 + x)/(3) * 3`

`264 = 157 + x`

`x = 264 - 157`

`x = 107`