Question

A car is running at a speed of 64 km/h to cover a certain distance in 40 min. At what speed should the car run to reduce the time of the journey to 30 min?
1. 84.78 km/h
2. 74.65 km/h
3. 54 km/h
4. 85.33 km/h

Answer 1

Correct Answer - Option 4 : 85.33 km/h

Given: 

Speed of car = 64 km/hr

Time = 40 min

Formula used:

Distance = speed × time

Concept used:

To convert km/hr to m/s multiply with 5/18

Calculation:

Speed of car = 64 km/hr

Distance = 64 × 40/60 = 128/3 km

Speed = Distance/time

⇒ (128/3)/(1/2)

⇒ 85.33 km/hr

∴ The speed of the car is 85.33 km/hr