Question 49620
Recall that "average" means the sum of the numbers divided by how many numbers you added up.

You need the average of 5 tests to be 90. The five scores will be:
86, 93, 80, 88, and x. Find the average:
{{{(86+93+80+88+x)/5 = 90}}} Add the numbers and multiply both sides by 5.
{{{347+x = 450}}} Subtract 347 from both sides.
{{{x = 103}}} is the required score on the fifth test.