Question

P, Q and R can do piece of work in 48, 60 and 80 days respectively. All three began to work together but P and Q left 12 and 16 days respectively before completion of the work. In how many days the work will be done?

A 12(5/12)days Correct Answer Incorrect Answer
B 12(7/12)days Correct Answer Incorrect Answer
C 30(1/3)days Correct Answer Incorrect Answer
D 6(7/12) days Correct Answer Incorrect Answer
E None of these Correct Answer Incorrect Answer

Solution

P’s one day’s work = 1/48days Q’s one day’s work = 1/60days R’s one day’s work = 1/80days Then, (x -12)/48 + (x -  16)/60 + (x )/80 = 1 (5(x-12)+4(x-16)+3x)/240 = 1 5x – 60 + 4x – 64 + 3x = 240 12x = 240 + 124 12x = 364 x = 364/12 x=91/3 ∴x = 30(1/3) days

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