If Mona and Sona together can finish a typing work in 18 days and Sona alone can finish it in 24 days, find the number of days in which Mona alone can finish the work.
Answer & explanation
Correct answer: option 4
Mona + Sona = 18 days, Sona = 24 days,
⇒ Mona + Sona = 4 (Efficiency)
⇒ Mona + 3 = 4
⇒ Mona = 1,
⇒ Time required by Mona to complete total work alone = \(\frac{72}{1}\) = 72 days, ..(\(\frac{Work}{Efficiency}\) = Time)