A car travels at a speed of 40 km/h for 15 minutes and at a speed of 72 km/h for the next 5 minutes. The average speed of the car for the whole journey is:
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 48 km/h.
Distance 1 = 40 × (15/60) = 10 km
Distance 2 = 72 × (5/60) = 6 km
Total distance = 10 + 6 = 16 km
Total time = 15 + 5 = 20 min = 1/3 h
Average speed = 16/(1/3) = 48 km/h