Means for Grouped Data For grouped data, the mean would be the sum of the frequencies times midpoints for each interval, that sum divided by N: For our previous distribution, the answer would be: i f i 01-10 1 11-20 3 1(5.5)+3(15.5)+2(25.5)+6(35.5) 21-30 2 4(45.5) = 498 / 16 = 31.125 31-40 6 41-50 4 Total 16
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