By which factor is the sound intensity decreased at 3 meters?

Which of the following best describes the circuit shown below?

Aswimming pool whose volume is 10 comma 000 gal contains water that is 0.01% chlorine. starting at tequals0, city water containing 0.003% chlorine is pumped into the pool at a rate of 5 gal/min. the pool water flows out at the same rate. what is the percentage of chlorine in the pool after 1 hour? when will the pool water be 0.006% chlorine?

If you held a stone over the mouth of a well and then let it go , what would happen to the stone? explain your answer.