Answer:
98%
Step-by-step 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.