Chapter 10.3 Puzzle
This assignment is due 48 hours after the Chapter Test is
given.
- Puzzle solutions are due by 5:00 PM two days after the Chapter
Test.
- Puzzles are worth 10 points of extra credit each.
- Answers must be accompanied by valid reasoning. Just like
the tests, the answer alone isn't enough!
- Please enter your solution in the text area at the bottom
of this page. DON'T FORGET TO GIVE YOUR NAME!
"Cleaning the
Pool"
It is the first day of your summer job at the local kiddie
pool with silly slides. After cleaning all the dead leaves out
of the pool you slowly fill it up with 10,000 gallons of clean
water. Your last chore for the day is to add the required four
pounds of chlorine granules. Or is it two pounds? Checking the
instructions left for you by the pool boss you realize you've
added twice the legal amount of chlorine to the pool!
(1) You decide to open the drain to let water flow out of
the pool, while adding fresh water to keep the volume constant.
The water drains out at a rate of 12 gallons per minute. Assuming
that the water in the pool stays well mixed, write a differential
equation for dC/dt, where C is the amount of chlorine
granules in the pool, measured in pounds, and t is time,
measured in minutes.
(2) It is 5:30 PM now. Do you have time to get the chlorine
concentration down to the correct level before the pool opens
tomorrow at 8 AM or will you be fired?
(3) Suppose the "clean" water you are adding actually
contains 0.00005 pounds of chlorine granules per gallon of water.
How does this affect your answer to Question (2)? You can assume
that the water originally in the pool (before you added anything)
was completely chlorine-free.
Don't forget to explain your answer
as clearly as possible.
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