SOLUTION: Working together, Pat, Lindsay and Robin can dig a drainage ditch in 2 3/4 hours. Working alone, Robin can do it in 9 hours, while Pat can do it 1/2 hour faster than Lindsay. How l

Algebra ->  Customizable Word Problem Solvers  -> Misc -> SOLUTION: Working together, Pat, Lindsay and Robin can dig a drainage ditch in 2 3/4 hours. Working alone, Robin can do it in 9 hours, while Pat can do it 1/2 hour faster than Lindsay. How l      Log On

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Question 141266: Working together, Pat, Lindsay and Robin can dig a drainage ditch in 2 3/4 hours. Working alone, Robin can do it in 9 hours, while Pat can do it 1/2 hour faster than Lindsay. How long will it take Lindsay to dig the ditch by herself?
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
let x=Lindsay

(1/9)+[1/(x-1/2)]+(1/x)=1/(11/4)

multiplying by x(x-1/2) __ x(x-1/2)+x+x-1/2=(4/11)x(x-1/2) __ x^2+(3/2)x-1/2=(4/11)(x^2-(1/2)x)

multiplying by 22 __ 22x^2+33x-11=8x^2-4x __ 14x^2+37x-11=0

use quadratic formula to find x