Three pipes of same capacity A,B,C can fill a tank in 6 hours. If there are only two pipes B and C of same capacity, the tank can be filled in?
Choose the correct answer
A) 2	B) 4	C) 9	D) 12	E) 16
The part of the tank filled by three pipes in one hour   = 1/6   =&gt; The part of the tank filled by two pipes in 1 hour   = 2/3 * 1/6 = 1/9.   The tank can be filled in 9 hours.   Answer:9
<result>C</result>
Three pipes of same capacity A,B,C can fill a tank in 6 hours. If there are only two pipes B and C of same capacity, the tank can be filled in?