Question

The weight of 72 books is 9kg. (a) find the weight of 80 such books. (b) how many books will weigh 6kg?

Answer 1

find weight of 1 book
9kg=9000gm
weight of 1 book=9000/72=125gm
weight of 80 books=80×125=10000gm=10kg
in 60 kg there will be 6000/125 =50

Answer 2

Calculating Weights

Given :-

Weight of 72 books = 9kg

To find :-

(a) Weight of 80 such books

(b) How many books will weigh 6 kg

Solution :-

(a)

Weight of 72 books = 9 kg

Weight of 1 book = 9/72 kg = 1/8 kg = 0.125 kg

Weight of 80 books = 80 × 0.125 = 10 kg

=> Weight of 80 books is 10 kg.

(b)

Let the no. of books which weigh 6 kg be z.

z × weight of 1 book = 6 kg

z × 0.125 = 6 kg

z = 6 / 0.125

z = 48

Another way to solve this is :-

1 book = 1/8 kg

1 kg = 8 books

6 kg = 8 × 6 books = 48 books

=> 48 books weigh 6 kg.