Question

Ram can do a piece of work in 5 days, and Sham can do the same in 10 days. With the help of Karan, they finished the work in 2 days. How many days would it take Karan to do the work ?
1. 5 days
2. 10 days
3. 15 days
4. 20 days

Answer 1

Correct Answer - Option 1 : 5 days

Given:

Ram can do a piece of work in 5 days

Sham can do the same in 10 days

Ram, Sham and Karan can do a together work in 2 days

Concept used:

Unitary Method

Calculation:

One day's work of Ram = 1/5

One day's work of Sham = 1/10

One day's work of Karan = [1/2 – (1/5 + 1/10)]

⇒ [1/2 – (2 + 1)/10]

⇒ (1/2 – 3/10)

⇒ (5 – 3)/10

⇒ 2/10 = 1/5

∴ Karan to do the work in 5 days.