Question

Mark (✓) against the correct answer
What least number is to be subtracted from each term of the ratio 15 : 19 to make the ratio 3 : 4?

(a) 3
(b) 5
(c) 6
(d) 9

Answer 1

(a) 3
Suppose that x is the number that is to be subtracted.
Then, (15 − x) : (19 − x) = 3 : 4

$$\begin{gathered} \Rightarrow \frac{15-x}{19-x}=\frac{3}{4} \\ \mathrm{Cross}\mathrm{multiplying},\mathrm{we}\mathrm{get}: \\ 60-4x=57-3x \\ \Rightarrow x=3 \end{gathered}$$