Question

A class of 18 students took a math test. Seven students had an average of 90. The other students had an average of 82.

What is the average for the whole class? Round to the nearest whole percent.

Answer 1

The important thing in this problem is to not average together the two averages.
That will not work, and will give you an incorrect answer.

You need to find the average grade of all 18 students by dividing the total number of points scored by all 18 students by 18.

First, find the total number of points the 90-average group got.
Do 90 * number of students who averaged 90.

Then find the total number of points the 82-aversge group got.
Do 82 * number of students who averaged 82.

Then add the points together.
Then divide by 18.