Question 927674
For a certain bathtub, it takes the cold water faucet 4 times as long to fill the tub as it does the hot water faucet. Left on together, the two faucets take 4 minutes to fill the tub. How long will it take the cold water faucet to fill the tub by itself?
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Let x = time (minutes) it takes for hot water faucet
then 
4x = time (minutes) for cold
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4(1/x + 1/(4x)) = 1
multiply both sides by 4x:
4(4 + 1) = 4x
4(5) = 4x
20 = 4x 
5 minutes = x (hot water)
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Time it takes for cold water faucet to fill tub by itself:
4x = 4(5) = 20 minutes