A person drives 60 km at 30 km/hr, then 30 km at 60 km/hr, and 45 km at 90 km/hr. What is the average speed?

Correct option is C

Given:
Distance1 = 60 km, Speed1 = 30
Distance2 = 30 km, Speed2 = 60
Distance3 = 45 km, Speed3 = 90
Formula Used:
Time = Distance ÷ Speed
Average Speed = Total Distance ÷ Total Time
Solution:
Time1 = 60 ÷ 30 = 2 hr
Time2 = 30 ÷ 60 = 0.5 hr
Time3 = 45 ÷ 90 = 0.5 hr
Total distance = 60 + 30 + 45 = 135 km
Total time = 2 + 0.5 + 0.5 = 3 hr
Average speed = 135 ÷ 3 = 45 km/hr