# Nate has scores of 85, 91, 89, and 93 on four tests. What is the least number of points he can get on the fifth test to have an average of at least 90?

Dec 13, 2016

$92$

#### Explanation:

Let $x$ stand for the number of points on the fifth test.

Then his average score will be:

$\frac{85 + 91 + 89 + 93 + x}{5} = \frac{358 + x}{5}$

We want this to satisfy:

$\frac{358 + x}{5} \ge 90$

Multiply both sides by $5$ to get:

$358 + x \ge 450$

Subtract $358$ from both sides to get:

$x \ge 92$

So Nate needs at least $92$ points.