Question

A boy runs for 20 min. at a uniform speed of 18km/h. At what speed should he run for the next 40min. so that the average speed comes 24km/hr

Answer 1

Answer:12km/h

Explanation:20min = 1/3 hrs.

Distance covered= 1/3X18 = 6km

40min=2/3 hrs.

Distance covered=?

Avg. Speed = Total distance covered ÷ Total time taken.

Total time= 1/3+2/3=3/3=1

Avg. Speed= 24km/hr

Total distance=6+x=24 km

x=18km

Speed= distance / time

= 18×2÷3 = 12km/h