A person drives 60 km at a speed of 30 km/hr, then 30 km at 60 km/hr, and finally 45 km at 90 km/hr. What is the average speed (in km/hr) for the entire trip?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 45 .
Total distance = 60 + 30 + 45 = 135 km
Time1 = 60 ÷ 30 = 2 hours
Time2 = 30 ÷ 60 = 0.5 hour
Time3 = 45 ÷ 90 = 0.5 hour
Total time = 2 + 0.5 + 0.5 = 3 hours
Average speed = Total distance ÷ Total time = 135 ÷ 3 = 45 km/hr