(a) Given,
Speed of sound in air (Va) = 340 m s-1
Speed of sound in water (Vw) = 1360 m s-1
Distance (d) = 1700 m
t = ?
V = Distance\over Time
Substituting the values for air, we get,
340 = 1700\over t
⇒ t = 1700\over 340 = 5 s
Therefore, the time taken by sound to travel in air = 5 s
(ii) Substituting the values for water, we get,
1360 = 1700\over t
⇒ t = 1700\over 1360 = 1.25 s