Ashish covers 72 km at a speed of 45 km/h by bike, 28 km at a speed of 4 km/h by bicycle, and another 160 km at a speed of 20 km/h by car. Find his average speed (in km/h) for the whole journey. (Rounded off to two decimal places)
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 15.66.
Total Distance:
⇒ 72 km (by bike) + 28 km (by bicycle) + 160 km (by car) = 260 km
Total Time:
⇒ Time taken by bike = Distance / Speed = 72 km / 45 km/h = 1.6 hours
⇒ Time taken by bicycle = Distance / Speed = 28 km / 4 km/h = 7 hours
⇒ Time taken by car = Distance / Speed = 160 km / 20 km/h = 8 hours
⇒ Total time = 1.6 + 7 + 8 = 16.6 hours
⇒ Average Speed: Average Speed = Total Distance / Total Time = 260 km / 16.6 hours ≈ 15.66 km/h
Therefore, Ashish's average speed for the whole journey is approximately 15.66 km/h.