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