Correct Answer - Option 1 : 8

**Given:**

A and B can finish a work in 6 days and 8 days respectively. They start the work after 2 days C joins them and the work is finished in total 3 days.

**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:**

total work will be 24 units.

A’s efficiency = 24/6 = 4

B’s efficiency = 24/8 = 3

Let the efficiency of C be c

ATQ,

7 × 2 + (7 + c) × 1= 24

⇒ 14 + 7 + c = 24

⇒ 21 + c = 24

⇒ c = 24 - 21 = 3

Time taken by C = 24/3 = 8 days