SOLUTION: It takes Jack eight minutes to sweep a porch. Lisa can sweep the same porch in 14 minutes. How long would it take if they worked together?

Question 1004498: It takes Jack eight minutes to sweep a porch. Lisa can sweep the same porch in 14 minutes. How long would it take if they worked together?

Found 2 solutions by josgarithmetic, stanbon:
Answer by josgarithmetic(39618) (Show Source): You can put this solution on YOUR website!
Their rates working together are simply to be summed. The rate of each must be arranged as HOW MUCH WORK per HOW MUCH TIME.

, PORCH/MINUTE

The question was, how much time? This means you want the reciprocal.
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
It takes Jack eight minutes to sweep a porch. Lisa can sweep the same porch in 14 minutes. How long would it take if they worked together?
----
Jack rate:: 1/8 job/min
Lisa rate:: 1/14 job/min
Together rate:: 1/x job/min
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Equation:
rate + rate = together rate
1/8 + 1/14 = 1/x
----
14x + 8x = 14*8
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22x = 14*8
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x = 5.09 min = 5min 5.4sec (time to do the job together)
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Cheers,
Stan H.
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