Correct Answer - Option 2 : 64/5 days

**Given:**

Kunal's efficiency = (Arun's efficieny)/4

**Calculation:**

Arun completes work alone = 4 × 16 = 64 days

Work done by Kunal in 1 day = (1/16)

Work done by Arun in 1 day = (1/64)

Work done by Kunal and Arun in 1 day = (1/16) + (1/64)

⇒ (4 + 1)/64

⇒ 5/64

⇒ 64/5 days

**Formula used**

**I**f X is ‘a’ times efficient than Y, and can complete work in y days, then formula for calculating the number of days, if both work together will be as follows:

[(ay)/(a + 1)] days

**Calculation:**

Number of days taken by Suman and Karan works together = [(4 × 16)/(4 + 1)]

⇒ 64/5 days