Write them in order from least to greatest,
11.9, 12.0, 12.3, 12.4, 12.4, 12.5, 12.7,12.8, 12.9, 13.1, 13.2, 13.8
then eliminate one from each side until you find the middle one,
12.5, 12.7
you have two middle, so you find the middle number in between them.
12.6 is the median.
It should take approximately 27 days using the water at an average of. 450 gallons per day
