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 the correct option:	A) 22	B) 28	C) 77	D) 12	E) 21
1/A + 1/28 + 1/C = 1/8 (Given)   Also given that A = 228 and 28 = 2C   =&gt; 1/228 + 1/28 + 2/28 = 1/8   =&gt; (1 + 2 + 4)/228 = 1/8   =&gt; 228/7 = 8   =&gt; 28 = 28 hours.Answer: 28
<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?