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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 - Mathematics

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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 days
Explanation:

(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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