A and B can do a piece of work together in 10 days, B and C can do the same work together in 15 days, while C and A can do the same work together in 20 days. In how many days can A, B and C do the same work, working together ?
Answer & explanation
Correct answer: option 4
A + B = 10 days,
B + C = 15 days,
C + A = 20 days,
⇒ Adding all the efficiencies,
⇒ 2(X + Y + Z) = 13
⇒ X + Y + Z = \(\frac{13}{2}\),
⇒ Time required by A + B + C to complete the work = \(\frac{60}{13/2}\) = \(\frac{120}{13}\) days, ..(\(\frac{Work}{Efficiency}\) = Time)