Explanation: Speed is expressed as v=d/t if we derive this to find t:
t=d/v =3750m/ 1500m/s = 2.5 s note it the time required for the wave to reach the sunken ship. So multiply it by 2 to to have the final time to reach back on the source which takes 5 s.
I may be wrong but does it mean it was revent? because i know shortly after someone dies your body becomes fully stiff so maybe it was recent and it's in the process off stiffening up
