Question

A train travels from A to B, a distance of 100 km, at a speed of 20 km/h. If it had gone two and a half times fast, how much earlier would it have arrived at B?

• A. 3 hours
• B. 2 hours
• C. Same time
• D. Insufficient data

Answer 1

The correct option is A

3 hours

Speed = $\frac{Distance}{Timetaken}$
Time taken = $\frac{Distance}{Speed}$
Time taken for the train to travel from A to B (100 km) at a speed of 20 km/h = $\frac{100}{20}$ = 5 hours
If the speed of the train was two and half times fast, then the speed would have been
= $\frac{20\times 5}{2}$ = 50 km/h
Time taken for the train to travel from A to B (100 km) at a speed of 50 km/h
= $\frac{100}{50}$ = 2 hours
Hence, the train would have arrived (5-2) = 3 hours earlier, if it travelled at two and half times its speed of 20 km/h.