Question

Sam will take four science tests this quarter. Her scores on three of the tests are shown below.

What does Sam need to score on the fourth test to ensure that she will have an average of 90% for all four tests?

Answer 1

98%

Explanation:

Test 1 - 83%

Test 2 - 91%

Test 3 - 88%

Test 4 - ?

If we use x to represent Test 4, we can create the following equation:

1/4 (83 + 91 + 88 + x) = 90

We find the average here by adding up the four test scores and dividing by 4.

Proceed to solve it:

1/4 (262 + x) = 90

262 + x = 360

x = 98

Therefore, Sam needs to get a 98% to have and average of 90% on all four tests.