Symbiosis National Aptitude Test SNAP 2016 Paper

A tap can fill a tank in 6 hours.
After half the tank is filled i.e. after 3 hrs.
Three more similar taps are opened i.e.
no. of taps to fill remaining half tank = 4 taps
when 1 tap is used = (3 hrs/1 tap)
when 4 taps are used = (3 hrs/4 taps)=45min
Total = 3 hrs + 45 min
∴ Total Time = 3 hours45 minutes.