POSSIBLE SOLUTION(S)

1. All this work is based on the following simplifications, assumptions and approximations:


We ignore air resistance. We assume the coin is dropped from ground level and its "echo" is heard at ground level. We approximate the speed of sound as 340 m/s.

2. The solution to this question uses the same time and distance formulas. In part one, we asked where the times added up to 10. This time, we wonder when the times are equal.

3. The solution to this question uses the same time and distance formulas and approach used in the previous two parts. This time, we wonder when the time it takes your coin to hit bottom is 15 times greater than the time it takes the sound of it hitting to return to the top.