A can do a piece of work in 10 days. B can do it in 15 days. With the assistance of C they completed the work in 5 days. Find in how many days C alone can do it?
Answer & explanation
Correct answer: option 3
A = 10 days, B = 15 days,
⇒ According to the question, with assistance of C, A + B can complete the work in 5 days.
⇒ \(\frac{30}{3 + 2 + C}\) = 5 days. ..(\(\frac{Work}{Efficiency}\) = Time)
⇒ \(\frac{30}{5 + C}\) = 5,
⇒ 30 = 25 + 5C
⇒ 5C = 5
⇒ C = 1. (Efficiency)
⇒ Time required for C to do total work alone = \(\frac{30}{1}\) = 30 days