A large tanker can be filled by two pipes A and B in 60 minutes 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 ?  Select the correct option
A) 15 min	B) 20 min	C) 27.5 min	D) 30 min	E) 35 min
et total time consumed in filling the tank is n.   (A+B)'s 1 minute work is 1/60 + 1/40 and (A+B) will take half of total time ie   (n/2)(1/60 + 1/40)----------(1)   and rest half will be filled by B only in half of total time means (n/2)(1/40)--(2)   (1)+(2)   (n/2)(1/60 + 1/40) + (n/2)(1/40)=1   n=30   ANSWER:30 min
<result>D</result>
A large tanker can be filled by two pipes A and B in 60 minutes 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 ?