Question

a and b working alone can finish a piece of work in 10 and 12 days .if they work at it alternatively for a day beginning with a in how many days will the work be finished

Answer 1

A can do in = 10 days

B in = 12 days

Total work = LCM of 10 and 12 = 60

1 day work of A = 1/10

1 day work of B = 1/12

1 unit work = 1 day work of A + 1 day work of b

= 1/12 + 1/10 = 11/60

As A and B will work alternatively so we will take day 1 of A and day 1 of B as 1 unit of work

Work done in first 10 days will be 11*5/60 = 55/60

Remaining work = 1 - 55/60 = 5/60

Now its A's turn on 11th day to complete the remaining work

So 10 + 1 = in 11 days work will be complete if A and B work alternatively