Question

The weight of 72 books is 9 kg. What is the weight of 40 such books?

Answer 1

The weight of 72 books = 9 kg
∴ The weight of 1 book =\(\frac{9}{72}\)
= \(\frac{1}{8}\)
∴ The weight of 40 books = \(\frac{1}{8}\times40\)
= 5 kg
Thus, the weight of 40 books is 5 kg.

Answer 2

Given :
The Weight of 72 books = 9kg i.e 9000 g
So, Weight of 1 book = \(\frac{9000}{72}=125\ \text{g}\)
Therefore, Weight of 40 book will be :
= 125 × 40g
= 5000 g i.e 5 kg
So, the Weight of 40 books = 5 kg