Motion In A Straight Line

A diving board is at at height of $h$ from the water surface. A swimmer standing on this board thrown a stone vertically upward with a velocity $16 \mathrm{~ms}^{-1}$. It reaches the water surface in a time of 5 s . In the next 0.2 s the diver can hear the sound from water surface. The speed of sound is (acceleration due to gravity $g=10 \mathrm{~ms}^{-2}$ )