Question

A can complete a work in 4 days and B can complete the same work in 6 days. B started the work and worked for one day, On the second day A joined B. Find the number of days to complete the whole work.

1. 2 days
2. 3 days
3. 8 days
4. 12 days
5. 16 days

Answer 1

Correct Answer - Option 2 : 3 days

Given:

A can do the work in 4 days

B can do the work in 6 days

Concept used:

Total work = Efficiency × Time period

Calculation:

Taking the L.C.M of 4 & 6

L.C.M of 4 & 6 = 12

⇒ One day work of A = 12/4 = 3

⇒ One day work of B = 12/6 = 2

Work completed by B in one day = 2

⇒ Remaining work = 12 – 2 = 10

⇒ Time A and B take to complete the remaining work = 10/(3 + 2) = 10/5 = 2

⇒ Total number of days to complete the work = 1 + 2 = 3

∴ The number of days in which work is completed is 3 days.