Question

the speed of the sound is 340m/s.a person fires a gun and its echo is heard after 1.5sec.find the distance of the gunman from the cliff from which the echo takes place

Answer 1

Time = Distance travelled/speed
Total distance = 55+55=110 m

because for an echo to be heard, the sound will go to the wall and then return.
t = d/s
= 110/330
= 1/3 = 0.33 secs