Question

Li has scores of 82.5, 84, 88.5, 92.5, and 94.5 on quizzes. What score must he get on the next quiz to have an average of at least 90?

Answer 1

98

Explanation

First, we need to give the next test a variable since we don't know what it is yet. We will name it "x". Since you are trying to find the average, you will have to add all 6 tests together and then divide it by 6 since there are 6 quizzes.

The equation would be:

82.5+84+88.5+92.5+94.5+x ≥ 90

6

Then, you should closely but not completely simplify that to:

442+x ≥ 90

6

Next, multiply each side by 6. Cancelling the "6" on the left:

442+x ≥ 540

Lastly, subtract 442 from each side of the equation. The 442 on the left cancels out, leaving x alone, and on the left, 540 minus 442 is 98:

x ≥ 98

Thus, Li has to earn at least a 98 on his next quiz in order to have an average of at least a 90. :)

-Question answered by Angelina M.

8th grade student