Problema Solution
Joe and Renee are building a fence. Joe can build a fence alone in 4 hours. If Renee starts helping Joe after he has already worked on the fence for 2 hours, they will finish the fence 90 minutes after she joins him. How long would it take Renee to build the fence alone?
Answer provided by our tutors
Joe's rate is: 1/4 fence per hour
Let 'x' represent the number of hours Renee need to build the fence alone.
Renee's rate is: 1/x fence per hour.
(1/4)*2 + (90/60)(1/4 + 1/x) = 1
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click here to see the equation solved for x
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x = 12 hr
Renee needs 12 hours to build the fence alone.