Question

Kamlesh worked $27$ days and completed $75$ percent of particular work. Then he took help of Lucifer and they together completed the remaining work in $5$ days . How long will Lucifer take to complete the same work, if he is working alone?

• A. $40$
• B. $45$
• C. $50$
• D. $52$

Answer 1

Answer: (B)

$45$

Kamlesh completed $75\%$ of the work in $27$ days.

So, work rate of kamlesh $=\frac{75}{27}=2.775$ per day.
Kamlesh and Lucifer completed $25\%$ remaining work in $5$ days.

Then work rate of kamlesh and Lucifer together $=\frac{25}{5}=5\%$ per day.
So, work rate of Lucifer $=5-2.77=2.23\%$ per day.
To complete $100\%$ work alone, Lucifer needs $=\frac{100}{2.23}=45$days.