Question

Sanjay and Amit can do a piece of work in 8 days. Amit alone can do it in 12 days. In how many days will Sanjay do it alone?
1. 20 days
2. 24 days
3. 16 days
4. 12 days

Answer 1

Correct Answer - Option 2 : 24 days

Given:

Time to complete the work by Sanjay and Amit together = 8 days

Time to complete the work by Amit alone = 12 days

Formula used:

Efficiency = Work done/Time

Calculations:

Let the efficiency of Sanjay and Amit be a and b respectively.

Let the total work be 24 units.

Efficiency of Sanjay and Amit together = a + b = 24/8

⇒ a + b = 3 units/day      ----(i)

Efficiency of Amit = b = 24/12

⇒ b = 2 units/day      ----(ii)

Efficiency of Sanjay = a = 3 - b

⇒ a = 3 - 2

⇒ a = 1 unit/day

Time to complete the whole work by Sanjay alone = 24/1 = 24 days

∴ Sanjay alone can do the whole work in 24 days.