P can do a work in 12 days. Q can do the same work in 10 days. If P and Q come together, both of them can complete the same work in how many days?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → \(5\frac{5}{11}\) days
A person who finishes a work in \(n\) days does \(\frac{1}{n}\) of it in one day; working together, their one-day works are added.
P’s one-day work \(\displaystyle =\frac{1}{12}\), Q’s \(\displaystyle =\frac{1}{10}\)
Together \(\displaystyle =\frac{1}{12}+\frac{1}{10}=\frac{5+6}{60}=\frac{11}{60}\)
Days \(\displaystyle =\frac{60}{11}=5\frac{5}{11}\)