Pipe A can fill a tank in 20 Mins and pipe B can fill it in 30 Mins. If both the pipes are opened in the empty tank. In how many Mins will it be fill exact half of the tank? Pick one.
A) 4 mins  B) 5 mins  C) 6 mins  D) 7 mins  E) 8 mins
Part filled A in 1 hr= (1/20)   Part filled B in 1 hr= (1/30)   Part filled by (A+B) together in 1 hr=(1/20)+(1/30)=1/12   So, The tank will be full in 12 mins   Time taken to fill Exact half tank = 12/2= 
<gadget id="calculator">12/2</gadget>
<output>6</output>
6 Mins.   Answer : 6 mins
<result>C</result>
Pipe A can fill a tank in 20 Mins and pipe B can fill it in 30 Mins. If both the pipes are opened in the empty tank. In how many Mins will it be fill exact half of the tank?