Nataliya D. answered • 03/20/13

Patient and effective tutor for your most difficult subject.

*Love this kind of problems!* :)

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Suppose that an experienced electrician can wire a room for **x** hours with productivity 1/x .

Then an apprentice electrician can wire a room for **2x** hours with productivity 1/(2x) .

On the one hand their productivity is 1/3 , and on the other hand their productivity is (1/x + 1/(2x)) .

Now we are ready to write equation

1/x + 1/(2x) = 1/3 LCD(x, 2x, 3) = 6x

(6 + 3)/(6x) = 2x/(6x) ---> 9/(6x) = 2x/(6x) --->** 2x** =** 9** hours