C can do a work alone in 120 days. B is twice as efficient as C and A is thrice as efficient as B. In how many days can they together complete the work?
Answer & explanation
Correct answer: option 1
C = 120 days,
According to the question,
A : B : C
⇒ 3 : 1
⇒ : 2 : 1
⇒ 6 : 2 : 1 (Efficiency)
⇒ Total work = 1 x 120 days = 120 units, ..(Efficiency × Days = Total work)
⇒ Time required by A + B + C to complete the total work = \(\frac{120}{6+2+1}\) = \(\frac{120}{9}\) = 13.33 days ..(\(\frac{Work}{Efficiency}\) = Time)