Subject: General Aptitude · Chapter: Time and Distance · Exam: 2011 · Marks: · Difficulty:
Two boys $A$ and $B$ start at the same time to ride from Delhi to Meerut, 60 km away. A travels 4 km an hour slower than $B, B$ reaches Meerut and at once turns back meeting A, 12 km from Meerut. A's rate was
(a)4 km/hr
(b)8 km/hr
(c)12 km/hr
(d)16 km/hr
Answer
Answer (as printed): B
Explanation
Let A's speed $=x \mathrm{km} / \mathrm{hr}$. Then, B's speed $=(x+4) \mathrm{km} / \mathrm{hr}$. Clearly, time taken by B to cover $(60+12)$ i.e., 72 km $$\begin{aligned} & =\text { Time taken by } A \text { to cover }(60-12) \text { i.e., } 48 \mathrm{km} \\ & \therefore \frac{72}{x+4}=\frac{48}{x} \Rightarrow 72 x=48 x+192 \Rightarrow 24 x=192 \Rightarrow x=8 . \end{aligned}$$ Hence, A's speed $=8 \mathrm{km} / \mathrm{hr}$.