# Jeannie's scores on her first four tests were 80, 65, 87, and 75. What will she have to score on on her next test to obtain an average of at least 80 for the term?

Jun 3, 2018

$97$

#### Explanation:

We can rearrange the terms in the formula for average from
$\text{average"="sum of set"/"number of terms in the set}$
to
$\text{sum of set"="average"*"number of terms in the set}$
Since the average we aiming for is $80$ and that will be the fifth term, then the sum of set will be
$80 \cdot 5$ which is $400$, we can solve for the fifth term but finding the differnce between $400$ and the sum of the stated four terms.
$400 - \left(80 + 65 + 87 + 75\right)$ to which the answer is $97$