A train running at a speed of 64 km/h takes 50 min to travel a certain distance. By how much should it increase its speed (in km/h) to travel the same distance in 40 min?

Question

Question

This question was previously asked in

RRB ALP Fitter 23 Jan 2019 Official Paper (Shift 2).

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Answer 1

Given:

Speed = 64 km/hr, Time₁= 50 min, Time₂= 40 min

Formula:

Distance =Speed × Time

Calculation

⇒ Distance = 64 km/hr × (50/60) hrs

⇒ Distance = (160/3) km

Now, calculate the speed by putting value of Time₂

⇒ (160/3) = (40/60)hrs × Speed

⇒ (160/3) × (60/40) = speed

⇒ Speed = 80 km/hr

New speed – Old speed = increase in speed

⇒ 80 – 64 = 16 km/hr

Short trick:

Initial time = 50 mins, New time = 40 mins

Time is decrease by 20%

As we know that when distance is constant speed is inversely proportional to time.

Given:

Old speed = 64 km/hr

Old speed we assume in above chart = 4 units

Difference between old speed and new speed = 1 unit.

⇒ 4 units = 64 km/h

⇒ 1 unit = 16 km/hr.