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

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

$\frac{x_1+x_2+x_3}{3} =88$

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

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

so

$\frac{x_1+x_2+x_3+x_4}{4} =90$

$x_1+x_2+x_3+x_4=360$ ----> 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.