rtaha2412 wrote:If Samson is filling a bathtub with COLD water, it will take him 6 minutes and 40 seconds, and if he fills it with HOT water, it will take him 8 minutes. If draining the tub takes 13 minutes and 20 seconds, how many minutes will it take to fill up the bath tub with both HOT and COLD water running while the plug is out, so the water is constantly draining?
16
12
8.6
5
4.75
Plug in tub = 40 liters.
Time for cold water = 20/3 minutes, so rate for cold water = w/t = 40/(20/3) = 6 liters per minute.
Time for hot water = 8 minutes, so rate for hot water = w/t = 40/8 = 5 liters per minute.
Time for drain = 40/3 minutes, so rate for drain = 40/(40/3) = 3 liters per minute.
Combined rate for all 3 = cold + hot - drain = 6+5-3 = 8 liters per minute.
Time to fill with all 3 running = w/r = 40/8 = 5 minutes.
The correct answer is
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