A tank is filled in 5 hours by three pipes A, B and C. The pipe C is twice as fast as B and B is twice as fast as A. How much time will pipe A alone take to fill the tank?
Answer: C
Suppose pipe A alone takes x hours to fill the tank.
Then, pipes B and C will take | x | and | x | hours respectively to fill the tank. |
2 | 4 |
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1 | + | 2 | + | 4 | = | 1 |
x | x | x | 5 |
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7 | = | 1 |
x | 5 |
x = 35 hrs.