Question

A team of two people A and B, who can complete a piece of work together in 40 days, begin the work. C joins them after 8 days and the work gets completed in 24 days after C joins them. in how many days can C alone complete the work?
1. 139 days
2. 100 days
3. 120 days
4. 128 days

Answer 1

Correct Answer - Option 3 : 120 days

Given:

A and B together can complete the work in 40 days

Concept:

Work = 1/Efficiency

Calculation:

⇒ Lets C alone do the work in p days

⇒ One day work of A and B = 1/40

⇒ 8 days work of A and B = 8/40 = 1/5

⇒ Remaining work = 1 - 1/5 = 4/5

⇒ One day work of A, B, and C = (1/40 + 1/p)

⇒ They all together can complete the 4/5 work in 24 days

⇒ (24/40 + 24/p) = 4/5

⇒ By solving, p = 120 days

∴ The required result will be 120 days.