Q147
ArithmeticSpeed, Time & Distance
A train travelling with uniform speed crosses two bridges of lengths 300m and 240m in 21 seconds and 18 seconds respectively. The speed of the train is
- a.72 km/hr
- b.68 km/hr
- c.65 km/hr
- d.60 km/hr
Answer: (A) 72 km/hr
The extra 60 m of bridge takes 3 extra seconds, so the speed is 20 m/s. 20 m/s × $\frac{18}{5}$ = 72 km/hr (the train is 120 m long). The other speeds do not fit both timings.