Question

Joan has earned grades of 88, 94, 92, and 98 on math tests so far. What must her next grade be to give her an average grade of 60?

Answer 1

Answer:

see the explanation

Step-by-step explanation:

Let

x ------> the next grade

we know that

To find the average grade sum the grades by the number of math test

so

$60=\frac{(88+94+92+98+x)}{5}$

solve for x

Combine liker terms in the right side  

$60=\frac{(372+x)}{5}$

Multiply by 5 both sides

$300=372+x$

Subtract 372 both sides

$300=372+x$

$x=-72$ -----> this is not make sense

The grade cannot be a negative number

so

For x=0

The minimum average grade is

$\frac{(372)}{5}=74.4$