Echo Time Calculation in Underwater Environments

[rrosa522]

Homework Statement

A seal sees a shark 53.0 m away and let's out a
squeal. If the speed of sound through sea water
is 1533 m/s, how long will it take for the echo
of the squeal to return to the seal?

Homework Equations

The Attempt at a Solution

i used the doppler effect formula and got 0.99m/s but it isn't the right answer

 

[haruspex]

i used the doppler effect formula and got 0.99m/s but it isn't the right answer

Doppler effect? What, apart from sound waves, is moving?
The question asks for a time, not a speed.
What is the sound echoing off?

I note the title mentions a submarine. Have you posted the text for the wrong question?