Test 4 Score

Let s = test 4 score

(88 + x)/2 = 90

Correct set up?

 

(88+88+88 + x)/4 = 90

(x + 264)/4 = 90
x + 264= 90*4
x = 360-264
x = 96 -> 4th test must be 96

 

Your set up was my first choice.

 

The average of a list of numbers is the sum divided by the number of numbers in the list.
To find the average of these 4 numbers we must first add them. We want to find the fourth number so call that x,
We do not know the first 3 numbers but we know their average is 88 so we know their sum is 3(88)= 264. We want (264+ x)/4= 90. 264+ x= 4(90)= 360. x= 360- 264= 96.

 

That's simple enough. Thanks.