A large tanker can be filled by two pipes A and B in 60 and 40 minutes respectively. How many minutes will it take to fill the tanker from empty state if B is used for half the time and A and B fill it together for the other half? Choose the correct choice from the following options:
A) 67 min  B) 45 min  C) 97 min  D) 30 min  E) 16 min
Part filled by (A + B) in 1 minute   = (1/60 + 1/40) = 1/24   Suppose the tank is filled in x minutes.   Then, x/2(1/24 + 1/40)   = 1   x/2 * 1/15 = 1 =&gt; x   = 30 min.   Answer: 30 min
<result>D</result>
A large tanker can be filled by two pipes A and B in 60 and 40 minutes respectively. How many minutes will it take to fill the tanker from empty state if B is used for half the time and A and B fill it together for the other half?