Time taken to hear the sound of tank 1 = 2 s

Time taken to hear the sound of tank 2 = 3.5 s

Time interval = 3.5 – 2 = 1.5 s

Distance between two tanks = 510 m

Velocity (V) = ?

V = Distance\over Time

= 510\over 1.5 = 340 ms^{-1}

Therefore, **the speed of sound = 340 m s ^{-1 }.**