A and B can complete a piece of work in 10 days. B and C can do it in 15 days. A and C can do it in 12 days. A, B and C together can complete it in how many days ?

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UP Police Constable Re-Exam 2024 Official Paper (Held On: 30 Aug 2024 Shift 1)
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  1. 10 days
  2. 15 days
  3. 8 days
  4. 17 days

Answer (Detailed Solution Below)

Option 3 : 8 days
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Detailed Solution

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Given:

A and B can complete the work in 10 days.

B and C can complete the work in 15 days.

A and C can complete the work in 12 days.

Formula used:

Work done per day = 1 / Number of days to complete the work

Calculation:

Work done per day by A and B:

(A + B) = 1/10 units per day

Work done per day by B and C:

(B + C) = 1/15 units per day

Work done per day by A and C:

(A + C) = 1/12 units per day

Adding all the equations:

(A + B) + (B + C) + (A + C) = 1/10 + 1/15 + 1/12

Finding the LCM of 10, 15, and 12:

LCM of 10, 15, and 12 = 60

1/10 = 6/60, 1/15 = 4/60, 1/12 = 5/60

2(A + B + C) = (6 + 4 + 5)/60 = 15/60 = 1/4

Work done by A, B, and C together:

A + B + C = 1/8 units per day

Total time taken by A, B, and C together:

Time = 1 / (A + B + C) = 8 days

∴ A, B, and C together can complete the work in 8 days.

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