Question

Class 10R sat a test.

The mean mark for the class was 70%.

There are 30 students in class 10R, 20 of whom are boys.
The mean mark for the boys in the test was 62%.

Work out the mean mark for the girls.

Answer 1

86%

Explanation:

30 students in the class with a mean average of 70% can be expressed as:

total class percent / 30 = 70%

Rearranged, this gives that the class achieved a total of 30x70 or 2100%.

20 boys in the class with a mean average of 62% can be expressed as:

total boys percent / 20 = 62%

Rearranged, this gives that the boys achieved a total of 20x62 or 1240%.

This means that the girls achieved 2100 - 1240 so 860%.

Because there are 30 students and 20 boys, there are 10 girls.

Then work out the mean with a total of 860% and 10 girls.

860/10 = 86%.