A tank is filled in eight hours by three pipes A, B and C. Pipe A is twice as fast as pipe B, and B is twice as fast as C. How much time will pipe B alone take to fill the tank?
Choose one
A) 16 hours  B) 28 hours  C) 18 hours  D) 19 hours  E) 10 hours
1/A + 1/B + 1/C = 1/8 (Given)   Also given that A = 2B and B = 2C   =&gt; 1/2B + 1/B + 2/B = 1/8   =&gt; (1 + 2 + 4)/2B = 1/8   =&gt; 2B/7 = 8   =&gt; B = 28 hours.   Answer:28 hours
<result>B</result>
A tank is filled in eight hours by three pipes A, B and C. Pipe A is twice as fast as pipe B, and B is twice as fast as C. How much time will pipe B alone take to fill the tank?