A alone can do a piece of work in 10 days. A and B together can do the same piece of work in $\frac{20}{3}$ days. A, B and C together can do the same piece of work in $\frac{40}{7}$ days. In how many days can B and C together do the same piece of work?
Answer & explanation
Correct answer: option 3
A = 10 days,
A + B = \(\frac{20}{3}\) days,
A + B + C = \(\frac{40}{7}\) days,
⇒ A + B = 6 (Efficiency)
⇒ 4 + B = 6,
⇒ B = 2,
Similarily,
⇒ A + B + C = 7
⇒ 6 + C = 7
⇒ C = 1,
Therefore, time required for B + C to complete the work = \(\frac{40}{3}\) days, ..(\(\frac{Work}{Efficiency}\) = Time)