Problema Solution

hot water faucet can fill sink in 9 minutes while it takes the cold water facuet 7 min. how long would it take to fill the sink if both facuets were on

Answer provided by our tutors

let


x = the minutes both faucets need to fill the sink together, x>0


the together rate if both faucets is: 1/x sink per min


the rate of the hot water faucet is: 1/9 sink per min


the rate of the cold water faucet is: 1/7 sink per min


1/9 + 1/7 = 1/x


by solving we find:


x = 63/16


x = 3 15/16 min


x = 3 min (15*60)/16 sec


x = 3 min 56 sec


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if both faucets are open it will take 3 min 56 seconds for the sink to be filled.