Two pipes A and B can fill a tank in 20 and 30 minutes respectively. If both the pipes are used together, then how long it will take to fill the tank ?
Select the correct option.
A) 10 mins	B) 12 mins	C) 15 mins	D) 20 mins	E) 25 mins
Explanation:   In this type of questions we first get the filling in 1 minute for both pipes then we will add them to get the result, as   Part filled by A in 1 min = 1/20   Part filled by B in 1 min = 1/30   Part filled by (A+B) in 1 min = 1/20 + 1/30   = 1/12   So both pipes can fill the tank in 12 mins.   Option 12 mins
<result>B</result>
Two pipes A and B can fill a tank in 20 and 30 minutes respectively. If both the pipes are used together, then how long it will take to fill the tank ?