Correct Answer - Option 4 : 2.4

**Given:**

The efficiency of C to complete a work is 3 times more than the efficiency of A to complete the work. B can finish the work in the same time as A and C together finish the work. If A takes 12 days to finish the work.

**Formula:**

If A and B can together finish it in t days with A and B finishing the work in a and b days respectively,

1/a + 1/b = 1/t

**Calculation:** C A

Efficiency 4 1

Days 1 4

A takes 12 days to finish the work

Total work = 12 × 1 = 12

Time taken by A and C = total work/efficiency = 12/4 + 1 = 12/5 = 2.4 days

So, B will take 2.4 days