Correct Answer - Option 2 : 60 days
Given:
A and B can complete the work in 20 days
Concept:
Work = Efficiency × Days
Calculation:
Let be assume one day work of A = 1/A and one day's work of B = 1/B
⇒ One day work of A and B together = 1/20
⇒ "A" completed 40% of work in = 10 days
⇒ "A" completed 40% of work in = 10 × (100/40) = 25 days
⇒ "A" alone can complete the work in = 25 days
⇒ B alone can complete the work in = 1/25 + 1/B = 1/20
⇒ B can complete the work in = 100 days
⇒ B can complete 60% of work in = (100 × 3/5) = 60 days
∴ The required result will be 60 days.