Pipe A can fill in 20 minutes and Pipe B in 30 mins and Pipe C can empty the same in 40 mins.If all of them work together, find the time taken to fill the tank
Choose the correct choice
A) 17 1/7 mins B) 20 mins C) 8 mins D) 9 mins E) none of these
17 1/7 mins = 20   B = 30   C = -40   LCM = 120   =&gt; 17 1/7 mins = 6,TIMES   B = 4   C = -3   =&gt; 17 1/7 mins+B-C   = 7   TIME T17 1/7 minsKEN TO FILL THE T17 1/7 minsNK = 120/7 MINS = 17 1/7 MINS   17 1/7 minsNSWER:17 1/7 mins
<result>A</result>
Pipe A can fill in 20 minutes and Pipe B in 30 mins and Pipe C can empty the same in 40 mins.If all of them work together, find the time taken to fill the tank