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:

Given that there are 30 students in class 10R and the mean marks for the entire class was 70%. Therefore,

• total mark of class = 70 x 30 = 2100

Given that there are 20 boys in the class and the mean marks for the boys was 62 %. Therefore,

• total mark of boys = 62 x 20 = 1240

To calculate the mean mark for the girls we need to find the total number of girl and total mark of girls.

• total number of girl = 30 - 20 (boys) = 10
• total mark of girls = total mark of class - total mark of boys = 2100 - 1240 = 860
• mean mark for girls = 860 / 10 = 86