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Question 615335: Jack, Kay, and Lynn deliver advertising flyers in a small town. If each person works alone, it takes Jack 4 hours to deliver all the flyers, and it takes Lynn 1 hour longer than it takes Kay. Working together, they can deliver all the flyers in 40% of the time it takes Kay working alone. How long does it take Kay to deliver all the flyers alone?
Thanks
Answer by lwsshak3(11628)   (Show Source):
You can put this solution on YOUR website! Jack, Kay, and Lynn deliver advertising flyers in a small town. If each person works alone, it takes Jack 4 hours to deliver all the flyers, and it takes Lynn 1 hour longer than it takes Kay. Working together, they can deliver all the flyers in 40% of the time it takes Kay working alone. How long does it take Kay to deliver all the flyers alone?
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let x=hrs Kay takes to do the job alone
1/x= Kay's work rate
x+1=hrs Lynn takes to do the job alone
1/(x+1)=Lynn's work rate
4=hrs Jack takes to do the job alone(given)
1/4 =Jack's work rate
.4x=hrs to complete the job working together
..
.4x/x+.4x/(x+1)+.4x/4=100% of the job
.4+.4x/(x+1)+.x=1
multiply by 10
4+4x/(x+1)+x=10
LCD:(x+1)
4x+4+4x+x^2+x=10x+10
x^2-x-6=0
(x-3)(x+2)=0
x=-2 (reject, x>0)
or
x=3
ans:
hrs Kay takes to do the job alone=3
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