A works twice as fast as B. If B alone can complete a piece of work in 12 days, in how many days can A and B together finish the work?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 4 days
Working twice as fast means doing the same work in half the time.
A alone takes \(\displaystyle \frac{12}{2}=6\) days
One-day work of A and B \(\displaystyle =\frac{1}{6}+\frac{1}{12}=\frac{2+1}{12}=\frac{1}{4}\)
Together they finish the work in 4 days.