mysseo wrote:Working alone at its own constant rate, a machine seals k cartons in 8 hours, and working alone at its own constant rate, a second machine seals k cartons in 4 hours. If the two machines, each working at its own constant rate and for the same period of time, together sealed a certain number of cartons, what percent of the cartons were sealed by the machine working at the faster rate?
A. 25%
B. 33 and 1/3 %
C. 50%
D. 66 and 2/3 %
E. 75%
Let k = 8 cartons.
Rate for the faster machine = w/t = 8/4 = 2 cartons per hour.
Rate for the slower machine = w/t = 8/8 = 1 carton per hour.
Each hour:
(cartons produced by the faster machine)/(total cartons produced) = 2/(2+1) = 2/3 = 66 2/3%.
The correct answer is
D.
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