Question

There are 10 girls and 20 boys in a class

They take a test

The mean mark for the class is 70
The mean mark for boys is 62
Work out the mean for the girls

Answer 1

86

Explanation:

Let g = total score of all girls.

Let b = total score of all boys.

mean = (sum of numbers)/(number of numbers)

Boys:

b/20 = 62

b = 20 × 62

b = 1240

Class:

(g + 1240)/30 = 70

g + 1240 = 30 × 70

g = 2100 - 1240

g = 860

Girls:

mean = 860/10

mean = 86