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
[tex]\frac{x_1+x_2+x_3}{3} =88[/tex]
[tex]x_1+x_2+x_3=264[/tex] ----> equation A
How many points does he need on his last test to raise his mean test score to 90 points?
so
[tex]\frac{x_1+x_2+x_3+x_4}{4} =90[/tex]
[tex]x_1+x_2+x_3+x_4=360[/tex] ----> equation B
substitute equation A in equation B
[tex]264 + x_4 = 360[/tex]
solve for x_4
[tex]x_4 = 360-264[/tex]
[tex]x_4 = 96[/tex]
Therefore
Kevin needs 96 points on his last test to raise his mean test score to 90 points.
