SOLUTION: A local dairy has three machines to fill half-gallon milk cartons. The machines can fill the daily quota in 6 hours, 7 hours, and 7.5 hours, respectively. Find how long it takes to

Question 351477: A local dairy has three machines to fill half-gallon milk cartons. The machines can fill the daily quota in 6 hours, 7 hours, and 7.5 hours, respectively. Find how long it takes to fill the daily quota if all three machines are running.
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
A local dairy has three machines to fill half-gallon milk cartons. The machines can fill the daily quota in 6 hours, 7 hours, and 7.5 hours, respectively. Find how long it takes to fill the daily quota if all three machines are running.
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Equation:
rate + rate + rate = together rate
1/6 + 1/7 + 2/15 = 1/x
Multiply thru by 630x to get:
105x + 90x + 84x = 630
279x = 630
x = 2.26 hrs (time to do the job together)
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Cheers,
Stan H.
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