Question 817015: Kiana's average test score after 3 tests was 89%. After the 4th test her average raised to 91%. What was Karina's score on the 4th test?
Answer by FightinBlueHens(27)   (Show Source):
You can put this solution on YOUR website! The first 3 tests that Kiana took, when divided by 3, gives you an average of 89, so if you multiply 89 by 3, you'll find Kiana's score for the first 3 tests added together.
You need to find what percent Kiana got on her 4th test so you can divide it by 4, to get the new average, which is 91.
So if the total score after 3 tests is 89x3, that is 267.
267+y is the total score of Kiana's 4 tests.
(267+y)/4 is the average of the 4 tests Kiana took, and we know that that's 91, so
(267+y)/4=91, so you just have to solve for y, which is her new score.
267+y=91*4
91*4=364
267+y=364
y=97
|
|
|
