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.