Answer: 4500 m
Step-by-step explanation:
Within 6 seconds the signal will cover = 1500m/second x 6 seconds = 9000 meters
As it is an echo sounder, it has covered twice the distance; one phase of going and one phase of coming
We need to calculate one phase of the distance that will give the actual depth:
So the distance will be 9000/2 = 4500 meters
Therefroe, the water depth will be 4500 meters