A, B and C can do a piece of work in 10, 12 and 15 days respectively. They began the work together but A left after 2 days and B left 3 days before the completion of the work. How long did the work last? MCQ with Answer and Explanation
A, B and C can do a piece of work in 10, 12 and 15 days respectively. They began the work together but A left after 2 days and B left 3 days before the completion of the work. How long did the work last?
A. 7 days
B. 5 days
C. 8 days
D. 6 days
Answer: Option A
Solution (By JKSSB Mock Tests)
Total work = LCM(10, 12, 15) = 60 units. Efficiency of A = 6, B = 5, C = 4. Let the total time be x days. A worked for 2 days. B worked for (x - 3) days. C worked for x days. Total work = 2*6 + (x - 3)*5 + x*4 = 60 => 12 + 5x - 15 + 4x = 60 => 9x - 3 = 60 => 9x = 63 => x = 7 days.
A and B can do a piece of work in 12 days, B and C in 15 days, and C and A in 20 days. If A, B and C work together, in how many days will they complete the work?
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