Question

Steve goes on a 40-km bike ride. He covers the first half of the distance averaging a speed of 15 km/hr. In order to average 20 km/hr for the entire trip, how many kilometers per hour must his average speed be during the second half of the trip?

Answer 1

30 km/hr

Explanation:

Answer 2

Speed required to cover second half of distance = 30 km/hr

Explanation:

Total distance Steve traveled = 40 km

He covers the first half of the distance averaging a speed of 15 km/hr.

So he covers 20 km at a speed of 15 km/hr.

`\texttt{Time taken to cover first half = }(20)/(15)=1.33 hours`

We need to find in order to average 20 km/hr for the entire trip , how many kilometers per hour must his average speed be during the second half of the trip.

`\texttt{Total time taken = }(40)/(25)=2 hours`

So he need to cover second half distance in (2 - 1.33) hours = 0.67 hours.

`\texttt{Speed required = }(20)/(0.67)=30 km/hr`

Speed required to cover second half of distance = 30 km/hr