Question

Two friends $A$ and $B$ are $30$ km apart and they start simultaneously on motorcycles to meet each other. The speed of $A$ is $3$ times that of $B$. The distance between them decreases at the rate of $2$ km per minute. Ten minutes after they start $A^{\prime }s$ vehicle breaks down and $A$ stops and waits for $B$ to arrive. After how much time (in minutes) A started riding, does B meet A ?

• A. $15$
• B. $20$
• C. $25$
• D. $30$

Answer 1

The correct option is B $20$

Let speed of $B=Vkm/hr$
Let speed of $A=3Vkm/hr$
Given $4r=2\times 60km/hr\Rightarrow V=30km/hr$
Distance covered by then after $10min.=2\times 10=20km$
So, remaining distance $=(30-20)km=10km$
Time taken by $B$ to cover $10km=\frac{10}{30}=20min$