Correct Answer - Option 3 : 18
Concept:
Average Speed = Total Distance/Total time
Calculation:
A man travels first 50 km at 25 kmph
Time taken to travel 50 km = 50/25 = 2 hours
Next 40 km at 20 kmph and,
Time taken to travel 40 km = 40/20 = 2 hours
Last 90 km at 15 kmph
Time taken to travel 90 km = 90/15 = 6 hours
Total distance = 180 km
Total time = 10 hour
Average speed = 180/10 = 18 km/hr
∴ His average speed for the whole journey (in Kmph) is 18 km/hr