Practicing Success
When operated separately, pipe A takes 5 hours less than pipe B to fill a cistern, and when both pipes are operated together, the cistern gets filled in 6 hours. In how much time(in hours) will pipe B fill the cistern, if operated separately? |
15 18 10 9 |
15 |
A = (x - 5) hrs, B = x hrs Efficiency α \(\frac{1}{Time}\) Therefore, A : B = x : x -5 (Efficiency) ⇒ A + B = x + x - 5 = 2x - 5, ⇒ Time to fill tank = x\(\frac{x-5}{2x - 5}\) = 6, ⇒ \( {x }^{2 } \) - 5x = 12x - 30, ⇒ \( {x }^{2 } \) - 17x + 30 = 0, ⇒ (x - 15)(x - 2) = 0, ⇒ x = 15, 2, Therefore, B will fill the cistern in 15 hrs. |