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

86

Step-by-step 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