Question

In a class the average weight of girls is 45 kg and the average weight of boys of the same class is 63 kg. if the number of girls and boys in the class is in the ratio 5 : 4 the average weight of the whole class is?
1. 48 kg
2. 50 kg
3. 53 kg
4. 51 kg
5. 52 kg

Answer 1

Correct Answer - Option 3 : 53 kg

GIVEN:

The average weight of girls = 45 kg 

the average weight of boys = 63 kg

the ratio of number of girls and boys = 5 : 4

EXPLANATION:

number of girls = 5x

number of boys = 4x

∴ required average = \(\frac{5x\times 45+4x \times 63}{5x+4x}\)

\(\Rightarrow \frac{9x(25+28)}{9x} \\average= 53kg\)