# 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

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

• 15 days

• 18 days

• 20 days

• 25 days

#### 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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