A class has 30 students. The mean height of the 14 boys is 1.52m. The mean height of all the students is 1.48m. Work out the mean height of the girls.

The mean height of all the students is 1.48m which means that the total height of all the students is 30 * 1.48m = 44.4m. The contribution due to the boys is 14 * 1.52m = 21.28m. Therefore the total height of the girls is 44.4m - 21.28m = 23.12m. There are 30 - 14 = 16 girls in the class, so the mean height of the girls is 23.12 / 16 = 1.45m. Remember to double check the answer: [(16 * 1.45m) + (14 * 1.52m)] / 30 = 1.48m which is correct.