Answer:
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%.