Question

A train runs at $60$ km/h but halts for a fixed time every clock hour. Due to halts, its average speed becomes $50$ km/h. Find the duration of each halt.

• A. 8 minutes
• B. 10 minutes
• C. 12 minutes
• D. 14 minutes

Hint:

When halts occur “every hour” in the clock sense, compare distance covered in one hour at average speed with what would be covered at running speed to get running time and hence the halt duration.

Answer 1

The Correct Option is B

In one clock hour, the train covers $50$ km on average. At running speed $60$ km/h, the running time used to cover $50$ km is $50/60$ hour $=5/6$ hour $=50$ minutes.
Hence, within each clock hour, remaining time is the halt: \[ 60\ \text{minutes} - 50\ \text{minutes} = 10\ \text{minutes}. \] \[ \boxed{10\ \text{minutes}} \]