Question

the mean weight of 120 students of b.com class is 60 kgs the mean weight of boys is 55 kgs and that of girls is 45 kgs find the number of boys and girls

Answer 1

Answer:

Let the number of boys be B and the number of girls, G. Let us form the equation from the given statements.

B + G = 150 … (1).

The total weight of boys and girls is

70B + 55G = 150*60 = 9000 … (2)

The HCF in (2) is 5, so dividing right through by 5 we get

14B + 11G = 1800 … (3)

Multiply (1) by 11 to get

11B + 11G = 150*11 = 1650 … (4).

Subtract (4) from (3) to get

14B + 11G -11B - 11G= 1800 - 1650, or

3B = 150. or B = 50, then G = 150 - 50 = 100.

Check: Total weight of B and G = 50*70 + 100*55 = 3500+5500 = 9000.

Answer: Boys = 50, Girls = 100.