One reservoir has four taps. Using the first takes two days to saturate the reservoir, the second tap three days, the third four days and the last one 6 hours.
What time will it last to fill the reservoir using all 4 taps at once?

Because there are 24 hours in one day, in one hour fills the first tap 1/48, the second tap
1/72, the third tap 1/96 and the fourth tap fills 1/6 of the reservoir. That is all together
(6+4+3+48) / 288 = 61/288. The reservoir will be full in 288/61 hours, which is 4 hours
43 minutes and about 17 seconds.