Two pipes A and B can fill a tank in 10 minutes and 20 minutes respectively. If both the taps are opened simultaneously, and the tap A is closed after 5 minutes, then how much more time will it take to fill the tank by tap B?
Choose the correct choice from the following options
A) 5min
B) 6min
C) 10min
D) 7min
E) 12min
Part filled in 5 min. = 5(1/10 + 1/20) = 5*3/20 = 3/4   Remaining part = 1 - 3/4 = 1/4   Part filled by B in 1min. = 1/20   1/20 : 1/4 :: 1:x   x = 1/4 *1 * 20= 
<gadget id="calculator">1/4 *1 * 20</gadget>
<output>5</output>
5min   5minnswer is 5min
<result>A</result>
Two pipes A and B can fill a tank in 10 minutes and 20 minutes respectively. If both the taps are opened simultaneously, and the tap A is closed after 5 minutes, then how much more time will it take to fill the tank by tap B?