A boy receives the echo of his clap reflected by a nearby hill 0.8s later....

A boy receives the echo of his clap reflected by a nearby hill 0.8s later. How far is he from the hill?

Time for echo both ways = 0.8
Therefore time for echo in 1 way = 0.8/2 = 0.4
Distance = Speed x time
Distance = 340 x 0.4
Distance = 136m

There is an explanation video available below.

A boy receives the echo of his clap reflected by a nearby hill 0.8s later….