Answer:
0.1 sec
Explanation:
frequency of the clicks produced = 55 kHz = 55000 Hz
depth of the bottom of ocean from the dolphin = 75 m
we know that the speed of sound in water is generally accepted to be ≅ 1480 m/s.
the total distance traveled by the sound from the dolphin, to the bottom of the ocean, and then back to the dolphin = 2 x 75 = 150 m
time elapsed will then be
time = distance traveled ÷ speed of sound
time = 150/1480 ≅0.1 sec