SOLUTION: It takes Sarah 15 min to pick apples from the tree in her backyard. Lisa takes 25 min. How long will it take them working together?

Algebra ->  Rate-of-work-word-problems -> SOLUTION: It takes Sarah 15 min to pick apples from the tree in her backyard. Lisa takes 25 min. How long will it take them working together?      Log On


   

Question 663482: It takes Sarah 15 min to pick apples from the tree in her backyard. Lisa takes 25 min. How long will it take them working together?
Found 2 solutions by stanbon, jerryguo41:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
It takes Sarah 15 min to pick apples from the tree in her backyard. Lisa takes 25 min. How long will it take them working together?
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Sarah rate: 1/15 job/min
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Lisa rate: 1/25 job/min
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Together rate: 1/x job/min
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Equation:
rate + rate = together rate
1/15 + 1/25 = 1/x
25x + 15x = 15*25
40x = 15*25
x = (3/8)25 = 9 3/8 minutes (time to do the job together)
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Cheers,
Stan H.

Answer by jerryguo41(197) About Me  (Show Source):
You can put this solution on YOUR website!
(rate of person a)*time + (rate of person b)*time = 1
rate of person a = 1%2F15 (every 15 min she gets one apple)
rate of person b = 1%2F25 (every 25 min she gets one apple)
%281%2F15%29t%2B%281%2F25%29t=1
Clear Fractions
75%28%281%2F15%29t%2B%281%2F25%29t%29=75+
5t%2B3t=75
8t=75
t=9.375
or 9 min and 22.5 seconds