If a truck moves at a constant speed of 30 km/h for 1 kilometre and 45 km/h for the next 1 kilometre. What is the average speed of the truck?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is Option 2 i.e. 36 km/h.
Average speed = Total distance/Total time
Time taken to cover 1 km = 1/30
Time taken to cover the next 1 km = 1/45
Average speed = 2/(1/30 + 1/45)
⇒ 2/(3 + 2)/90 = 2/5/90 = 36 km/hr