A and B Can Do a Piece of Work in 6 and 12 Days, Respectively. They (Both) Will Complete the Work in How Many Days? - Mathematics


A and B can do a piece of work in 6 and 12 days, respectively. They (both) will complete the work in how many days?


  • 9 days

  • 18 days

  • 6 days

  • 4 days



4 days


A's 1 day's work = `1/6`

B's 1 day's work = `1/12`

(A+ B)'s 1 day's work = `1/6+1/12`

= `(2+1)/12=3/12=1/4`

Hence, both will complete the work in 4 days.

Second Method

Here, x = 6

and y = 12

∴ Time taken by (A+ B) = `(xy)/(x+y)`

= `(6xx12)/(12+6)` = 4 days

Concept: Time and Work (Entrance Exam)
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