Given: Ali can complete a piece of work = 8 days Balvinder can complete a piece of work = 10 days Ali, Balvinder and Chander can complete a piece of work = 4 days Formula used: Work done = Time × Efficiency Calculation: LCM of 8, 10 and 4 is 40 Work done by Ali in 1 day = 40/8 = 5 units Work done by Balvinder in 1 day = 40/10 = 4 units Work done by Ali, Balvinder and Chander together = 40/4 = 10 units According to the question Chander alone can finish the work = (Work done by Ali, Balvinder and Chander) – (Work done by Ali and Balvinder) ⇒ (10 – 9) units = 1 unit Chander alone finish the work = 40/1 = 40 days ∴ Required time to complete the work by Chander is 40 days