Statistics

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Mean (x̄) = Σfixi / Σfi Where: - fi = frequency of ith class - xi = class mark (mid-point) of ith class - Class mark = (Upper limit + Lower limit) / 2…

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Mean (x̄) = a + Σfidi / Σfi Where: - a = assumed mean (any value, preferably a class mark) - di = xi - a (deviation from assumed mean) - This method reduces calculation work when xi values are large…

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Mean (x̄) = a + h × (Σfiui / Σfi) Where: - a = assumed mean - h = class interval size - ui = (xi - a) / h - Used when di values have a common factor (usually the class size)…

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Class mark (or mid-point) is the representative value of a class interval. Class mark = (Upper class limit + Lower class limit) / 2 Example: For class 20-30, class mark = (20 + 30) / 2 = 25 It represe…

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Mode = l + [(f1 - f0) / (2f1 - f0 - f2)] × h Where: - l = lower boundary of modal class - f1 = frequency of modal class - f0 = frequency of class before modal class - f2 = frequency of class after mod…

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The modal class is the class interval with the highest frequency in the frequency distribution. Example: If frequencies are 5, 8, 12, 7, 3 for classes 10-20, 20-30, 30-40, 40-50, 50-60 respectively, t…

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Cumulative frequency of a class = Sum of frequencies of that class and all preceding classes. Types: 1. Less than type: Shows number of observations less than upper boundary 2. More than type: Shows n…

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Median = l + [(n/2 - cf) / f] × h Where: - l = lower boundary of median class - n = total number of observations - cf = cumulative frequency before median class - f = frequency of median class - h = c…