A can do a piece of work in 15 days, but with the help of B, he can do it in 9 days. In what time can B do it alone?
Answer & explanation
Correct answer: option 1
A = 15 days, A + B = 9 days,
⇒ A + B = 5 (Efficiency)
⇒ 3 + B = 5,
⇒ B = 2,
⇒ Time required by B to complete work alone = \(\frac{45}{2}\) = 22.5 days, ..(\(\frac{Work}{Efficiency}\) = Time)