In the given question,Incidence of fluorosis in an area is 250, 320, 190, 300, 5000, 100, 260, 350, 320, and 160. And, incidence in ascending order is 100, 160, 190, 250, 260, 300, 320, 320, 350, 5000. Mean = 7250/10 = 725 Median = Mean (average) of 5th and 6th value = (260 + 300)/2 = 280Mode = 320Since extreme values (outliers) are present for incidence (20 and 5000), mean will not be an appropriate measure of central tendency,  Thus, median will be the most suitable measure of central tendency.