Question 358405
both together take 2 hours
so they do 1/2 the job in1 hour
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let smaller pipe take x hours
so it will do 1/x of the job in 1 hour
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second pipe takes x-3 hours
so it does 1/(x-3) of the job in 1 hour
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1/x + 1/(x-3)=1/2
x-3+x/x(x-3)=1/2
2x-3=1/2* x(x-3)
2(2x-3)=x(x-3)
4x-6=x^2-3x
x^2-3x-4x+6=0
x^2-7x+6=0
x^2-6x-x+6=0
x(x-6)-1(x-6)=0
(x-6)(x-1)=0
x=1 OR 6
x = 1 is not valid
so x=6 hours taken by the pipe alone
second pipe takes 6-3 = 3 hours to fill the tank
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m.ananth@hotmail.ca