Ashar can do a work in 40 days. He worked at it for 8 days and left the work, after which Aman joined the work and finished the remaining work in 16 days. How long will Aman take to complete the whole work?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 20 days
A person who finishes a work in 40 days does \(\frac{1}{40}\) of it each day. So the part Ashar did is found first; Aman did the rest, and his time for that part gives his time for the whole work.
Work done by Ashar in 8 days: \(\displaystyle \frac{8}{40}=\frac{1}{5}\)
Work left for Aman: \(\displaystyle 1-\frac{1}{5}=\frac{4}{5}\)
Aman does \(\frac{4}{5}\) of the work in 16 days
Whole work: \(\displaystyle 16\times\frac{5}{4}=20\) days