Question

In a school hall 2/5 of the chairs are red 3/7

are blue and the rest are yellow
If there are 24 yellow chairs, how many chairs are blue?

Answer 1

60

Explanation:

We can use 5·7 = 35 as a common denominator for these fractions. This tells us the fraction of red chairs is 2/5 = 14/35, and the fraction of blue chairs is 3/7 = 15/35. The rest of the (35 -14 -15)/35 = 6/35 chairs are yellow. This means the ratio of chair colors is ...

red : blue : yellow = 14 : 15 : 6

Multiplying this by 4 will give 24 yellow chairs:

4·14 : 4·15 : 4·6 = 56 : 60 : 24 . . . . red : blue : yellow chairs.

60 chairs are blue.