Without any stoppage, Sunil travels a certain distance at an average speed of 80 km/hr. With stoppages, he covers the same distance at an average speed of 60 km/hr. How many minutes per hour does he stop for?

Question

Question

This question was previously asked in

RRC Group D Previous Paper 3 (Held On: 19 Sep 2018 Shift 1)

Answer 1

Given:

Speed without stoppage = 80 km/h

Speed with stoppage = 60 km/h

Formula used:

Speed = Distance/Time

Calculation:

Distance travel by Sunil with the speed of 80 km/h in one hour,

Distance = speed × Time

⇒ Distance = 80 × 1 = 80 km

Distance travel by Sunil with the speed of 60 km/h in one hour,

Distance = speed × Time

⇒ Distance = 60 × 1 = 60 km

Now, the time is taken to cover the extra 20 km with the speed of 80 km/h

Time = Distance/Speed

⇒ Time = 20/80

⇒ Time = 1/4 hour = (1/4) × 60

⇒ Time = 15 minutes

∴ Sunil stops on an average 15 minutes per hour.Shortcut Trick

Given:

Speed excluding stoppages = 80 km/h

Speed including stoppages = 60 km/h

Formula used:

Minutes of stops per hour = [(Faster speed - Slower speed)/Faster speed] × 60

calculation:

Minutes of stoppages per hour = [(80 - 60)/80] × 60

= (20/80) × 60

= 15 min

∴ Sunil stops on an average 15 minutes per hour.