Three pipes A,B and C are attached to a tank.A and B can fill it in 20 and 30 minutes respectively while C can empty it in 15 minutes.If A,B and C are kept open successively for 1 minute each, how soon will the tank be filled?	Choose the correct answer:
A) 165 min
B) 166 min
C) 167 min
D) 168 min
E) 169 min
the term successively and NOT SIMULTANEOUSLY.AT THE END OF 3 mts, i/60 part of the tank is filled.we have to consider a three-minute block starting from 3 mts, 6 mts,9 mts....etc upto 177 mts. at the end of 165 mts,55/60 part of the tank was filled. at the end of the next suceessive minutes,i.e, 166,167th minute, the part filled is 5/60.so 55/60+5/60. this means the whole tank is filled at the end of 167 th minute.   ANSWER:167 min
<result>C</result>
Three pipes A,B and C are attached to a tank.A and B can fill it in 20 and 30 minutes respectively while C can empty it in 15 minutes.If A,B and C are kept open successively for 1 minute each, how soon will the tank be filled?