SOLUTION: A work crew has a new pump and an old pump. The new pump can fill a tank in 5 hours, and the old pump can fill the same tank in 7 hours. Write and solve and equation for the time i

Question 983015: A work crew has a new pump and an old pump. The new pump can fill a tank in 5 hours, and the old pump can fill the same tank in 7 hours. Write and solve and equation for the time it will take both pumps to fill one tank if the pumps are used together.
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
A work crew has a new pump and an old pump. The new pump can fill a tank in 5 hours, and the old pump can fill the same tank in 7 hours. Write and solve and equation for the time it will take both pumps to fill one tank if the pumps are used together.
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new pump rate:: 1/5 job/hr
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old pump rate:: 1/7 job/hr
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together rate:: 1/x job/hr
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Equation:
rate + rate = together rate
1/5 + 1/7 = 1/x
7x + 5x = 35
12x = 35
x = 35/12 = 2 11/12 hr = 2hr 55 min (time to do the job together)
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Cheers,
Stan H.
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