prude_sb wrote:
Working alone, printers X, Y, and Z can do a certain printing job, consisting of a large number of pages, in 12, 15, and 18 hours, respectively. What is the ratio of the time it takes printer X to do the job, working alone at its rate, to the time it takes printers Y and Z to do the job, working together at their individual rates ?
(A) 4/11
(B) 1/2
(C) 15/22
(D) 22/15
(E) 11/4
ratio of X/(Y+Z) rates=1/4/(1/5+1/6)=15/22
inverting, ratio of X/(Y+Z) times=22/15
D
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