Correct Answer - Option 3 : 135 days
Given:
Pen and pencil can together complete a work in 45 days
The pencil is twice efficient as pen
Formula Used:
Work = Efficiency × Time
Calculation:
Let the efficiency of Pen be p then the efficiency of Pencil is 2p
Total work = 45
The efficiency of Pen and pencil = 45/45
⇒ 1
The efficiency of pencil = 1 – p
⇒ 1 – p = 2p
⇒ p = 1/3
The efficiency of Pen = 1/3
Time = 45/(1/3)
⇒ 135 days
∴ The pen will alone complete the work in 135 days.