You drop.a stone from rest into a well that is 7.35m deep.how long does it take before you hear the splash

0.75 seconds

Since the well is 7.35 m deep time taken by the stone to reach the water is (2gh)^1/2 . Here h is 3.5 m and velocity of sound is 330 m/s thus time taken by the sound is 7.35/330 sec. Thus total time taken is (2gh)^1/2 + 7.35/330 sec.