Answer:
0.05773 sec
Step-by-step explanation:
We know that
time = distance/speed = d/V
for air
t1 = 117/355 = 0.3295 sec
for fresh water
t_2 = 117/1480 = 0.07905 sec
for metal
t_3 = 117/5490 = 0.02131 sec
So as we can see sound will reach through metal hand rail 1st, then through fresh water and then through air
1st = metal hand rail
2nd = fresh water
3rd = air
time difference between 1st and 2nd sound = t_2 - t_3 = 0.07905 - 0.02131 = 0.05773 sec