A, B and C can complete a piece of work in 10, 15 and 20 days respectively. They started together but A left after 2 days and B left 2 days before the completion of the work. Find the total number of days taken to complete the work. MCQ with Answer and Explanation
A, B and C can complete a piece of work in 10, 15 and 20 days respectively. They started together but A left after 2 days and B left 2 days before the completion of the work. Find the total number of days taken to complete the work.
A. 7 days
B. 9 days
C. 8 days
D. 6 days
Answer: Option C
Solution (By JKSSB Mock Tests)
Total work = LCM(10, 15, 20) = 60 units. Efficiency of A = 6, B = 4, C = 3. Let the total work last for x days. A worked for 2 days, so work done = 2 * 6 = 12 units. Remaining work = 60 - 12 = 48 units. B worked for (x - 2) days and C worked for x days. Therefore, 4(x - 2) + 3x = 48 => 4x - 8 + 3x = 48 => 7x = 56 => x = 8 days.
Explanation:
Let B's efficiency be 1 unit/day, so A's efficiency is 2 units/day. Combined efficiency = 3 units/day. Total work = 3 * 14 = 42 units. Time taken by A alone = 42 / 2 = 21 days.
No comments yet. Be the first to start the discussion!