Pipes A and B can fill a cistern in 8 and 24 minutes respectively. They are opened an alternate minutes. Find how many minutes, the cistern shall be full? Pick:  A) 16  B) 12  C) 18  D) 17  E) 13
1/8 + 1/24 = 1/6   6 * 2= 
<gadget id="calculator">6 * 2</gadget>
<output>12</output>
12   Answer: 12
<result>B</result>
Pipes A and B can fill a cistern in 8 and 24 minutes respectively. They are opened an alternate minutes. Find how many minutes, the cistern shall be full?