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MCQ

A and B together can do a piece of work in 12 days, while B alone can finish it in 30 days. A alone can finish the work in

#### Options

15 days

18 days

20 days

25 days

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#### Solution

**20 daysExplanation:**

(A + B)'s 1 day's work = `1/12`

B's 1 day's work = `1/30`

∴ A's 1 day's work = `1/12-1/30`

= `(5-2)/60=1/20`

**Second Method**

Here, x = 12 and y = 30

∴ Required number of days = `(xy)/(y-x)=(12xx30)/(30-12)`

= `(12xx30)/18` = 20 days

A alone can finish the work in 20 days.

Concept: Time and Work (Entrance Exam)

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