MathDB

Doing a Job Together and Alone

Source:

February 7, 2009

Problem Statement

A

and

B

together can do a job in

A

days;

<span class='latex-bold'>(A)</span>\ 1 \qquad <span class='latex-bold'>(B)</span>\ 3 \qquad <span class='latex-bold'>(C)</span>\ 6 \qquad <span class='latex-bold'>(D)</span>\ 12 \qquad <span class='latex-bold'>(E)</span>\ 2.8

and

C

can do it in four days; and

A

and

C

in

2\frac{2}{5}

days. The number of days required for

A

to do the job alone is:

<span class='latex-bold'>(A)</span>\ 1 \qquad <span class='latex-bold'>(B)</span>\ 3 \qquad <span class='latex-bold'>(C)</span>\ 6 \qquad <span class='latex-bold'>(D)</span>\ 12 \qquad <span class='latex-bold'>(E)</span>\ 2.8

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