A, B and C can do a piece of work in 11, 20 and 55 days respectively. In how many days work will be finished if A is assisted by B and C on alternative day?

Sure, let's solve this step by step:

Step 1: First, we need to find out the one day's work of A, B and C.

A's one day work = 1/11 B's one day work = 1/20 C's one day work = 1/55

Step 2: Now, let's find out the work done by A, B and C in two days (since B and C are working on alternate days).

Two days work = A's one day work + B's one day work + A's one day work + C's one day work Two days work = 1/11 + 1/20 + 1/11 + 1/55 Two days work = 2/11 + 1/20 + 1/55

Step 3: Calculate the above expression:

Two days work = 0.1818 + 0.05 + 0.01818 Two days work = 0.25

So, A, B and C together can finish 1/4th of the work in 2 days.

Step 4: Now, let's find out how many days they will take to finish the whole work.

Since they can do 1/4th of the work in 2 days, they will take 2 * 4 = 8 days to finish the whole work.

So, the work will be finished in 8 days if A is assisted by B and C on alternate days.