Question:
Mark (✓) against the correct answer:
The rates of working of two tapes A and B are in the ratio 2 : 3. The ratio of the time taken by A and B respectively to fill a given cistern is
(a) 2 : 3
(b) 3 : 2
(c) 4 : 9
(d) 9 : 4
Solution:
(b) 3:2
Rates at which taps $\mathrm{A}$ and $\mathrm{B}$ work $=2: 3$
The ratio of time taken by taps $\mathrm{A}$ and $\mathrm{B}$ to fill the cistern $=\frac{1}{\text { Rates at which taps } \mathrm{A} \text { and } \mathrm{B} \text { work }}$
$=\frac{1}{\frac{2}{3}}=\frac{3}{2}=3: 2$