Two pipes A and B can fill a tank in 12 and 24 minutes respectively. If both the pipes are used together, then how long will it take to fill the tank?  Choose the correct choice from the following options.
A) 5 minutes	B) 10 minutes	C) 9 minutes	D) 7 minutes	E) 8 minutes
Part filled by pipe A in 1 minute =1/12   Part filled by pipe B in 1 minute =1/24   Part filled by pipe A and pipe B in 1 minute=1/12+1/24=1/8   both the pipe together can fill the tank in 8 minutes   Answer is 8 minutes
<result>E</result>
Two pipes A and B can fill a tank in 12 and 24 minutes respectively. If both the pipes are used together, then how long will it take to fill the tank?