A and B together can complete a work in 20 days. A's efficiency is 12.5% more than B's. Find the time taken by B alone to complete the same work.

- 105/2 days
- 95/2 days
- 85/2 days
- 100/3 days
- None of these

Option 3 : 85/2 days

**Given:**

Time to complete the whole work by A and B together = 20 days

**Concept used:**

Total Wok Done = Number of Days × Efficiency

**Calculation:**

The ratio of efficiency of A and B = 112.5 : 100

⇒ 9 : 8

Let the efficiencies (work is done per day) of A, and B be 9x and 8x respectively.

Total Wok Done = Number of Days × Efficiency

⇒ 20 × (9x + 8x)

⇒ 20 × 17x

⇒ 340x

The time is taken by B alone to complete the work = 340x/8x

⇒ 85/2 days

**∴** **B can complete the whole work in 85/2 days.**

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