Question

Kevin will take 4 math tests this term. All of the tests are worth the same number of points. After taking the first 3 tests, his mean test score is 88 points. How many points does he need on his last test to raise his mean test score to 90 points?

Answer 1

Kevin needs 96 points on his last test to raise his mean test score to 90 points.

Explanation:

we know that

The mean score is the total of all scores divided by the total number of tests.

Let

x_1 ----> the score in the first math test

x_2 ----> the score in the second math test

x_3 ----> the score in the third math test

x_4 ----> the score in the fourth math test

we have

After taking the first 3 tests, his mean test score is 88 points

so

`(x_1+x_2+x_3)/(3) =88`

`x_1+x_2+x_3=264` ----> equation A

How many points does he need on his last test to raise his mean test score to 90 points?

so

`(x_1+x_2+x_3+x_4)/(4) =90`

`x_1+x_2+x_3+x_4=360` ----> equation B

substitute equation A in equation B

`264 + x_4 = 360`

solve for x_4

`x_4 = 360-264`

`x_4 = 96`

Therefore

Kevin needs 96 points on his last test to raise his mean test score to 90 points.