Answer:
Kevin needs 96 points on his last test to raise his mean test score to 90 points.
Step-by-step 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
![\frac{x_1+x_2+x_3}{3} =88](https://tex.z-dn.net/?f=%5Cfrac%7Bx_1%2Bx_2%2Bx_3%7D%7B3%7D%20%3D88)
----> equation A
How many points does he need on his last test to raise his mean test score to 90 points?
so
![\frac{x_1+x_2+x_3+x_4}{4} =90](https://tex.z-dn.net/?f=%5Cfrac%7Bx_1%2Bx_2%2Bx_3%2Bx_4%7D%7B4%7D%20%3D90)
----> equation B
substitute equation A in equation B
![264 + x_4 = 360](https://tex.z-dn.net/?f=264%20%2B%20x_4%20%3D%20360)
solve for x_4
![x_4 = 360-264](https://tex.z-dn.net/?f=x_4%20%3D%20360-264)
![x_4 = 96](https://tex.z-dn.net/?f=x_4%20%3D%2096)
Therefore
Kevin needs 96 points on his last test to raise his mean test score to 90 points.