If Robert can assemble a model car in 30 minutes and Craig can assemble the same model car in 20
minutes, how long would it take them, working together, to assemble the model car?
(A) 12 minutes
(B) 13 minutes
(C) 14 minutes
(D) 15 minutes
(E) 16 minutes
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5 comments:
30 x 20/ 30+20
600/50
12 MINUTES
ANSWER : A
A
12 minutes
12 minutes
let the work done(that is to assemble a model car) by both of them be W
therefore
the rate is
W/30 +W/20
=> 5W/60
=> w/12 minutes
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