4 taps are fitted in a tank in which some are inlet taps and some are outlet taps. Each inlet tap can fill the tank in 24 hours and each outlet tap can empty the tank in 8 hours. Find the number of outlet taps if the whole tank is emptied in 3 hours when all the 4 taps are open.
1
2
2
3
3
4
4
1
5
5