Pipes A and B together can fill a tank in 10 hours. Pipes B and C together can fill the same tank in 12 hours. Pipes C and A together can fill the same tank in 15 hours. In how many hours can pipe B alone fill the same tank?
Answer & explanation
Correct answer: option 1
Total Capacity = 60l
Adding the given efficiencies:
(A + B) + (B + C) + (C + A) = 6 + 5 + 4
⇒ 2(A + B + C) = 15
⇒ (A + B + C) = $\frac{15}{2}$ --------(i)
Efficiency of B = eff(A + B + C) - eff( A + C)
= $\frac{15}{2}$ - 4 (from eq.(i))
= $\frac{7}{2}$ ----------(ii)
Time taken by pipe alone to fill the tank of capacity 60l = $\frac{Capacity}{efficiency}$
= $\frac{60 \times 2}{7}$
= $\frac{120}{7}$ hours