Lesson 4 Formulas Flashcards
1
Q
Mean ( x̄ ) for ungrouped data
A
Mean ( x̄ ) = ∑ X / N
where: ∑X = sum of the measurements or values N = number of measurements
2
Q
Weighted mean ( x̄ )
A
x̄ = ∑XW / ∑W
where: x̄ = mean X = measurement or value W= weight
3
Q
Mean for Grouped data
The Classmark Formula
A
x̄ = ∑fXm / N
where: X = measurement or score f = frequency Xm = classmark N = total frequency
4
Q
Mean for Grouped data
The Coded Formula
A
X = x̄ am +( ∑fd / N) i
where: Xam = assumed mean f = frequency d = coded deviation N = total frequency i = class size
5
Q
Median for Grouped data
A
Median = l + (( N/2 - < cf) / fm) (i)
where: l = lower class boundary of the median class f = frequency <cf = less than cumulative frequency above the median class N = total frequency i = class size fm = frequency of the median class
6
Q
Mode for Grouped Data
A
Mode = lm + (( fm - fa) / 2fm – fa -fb) (i)
where: lm= lower class boundary of the modal class f = frequency fa = frequency above the modal class fb = frequency below the modal class i = class size fm = frequency of the modal class
7
Q
Decile of grouped data
A
l + ((kn - cf) / f) (i)
where: k = i / 10 i = decile term n = total frequency
8
Q
Quartile of grouped data
A
l + ((kn - cf) / f) (i)
where: k = i / 4 i = quartile term n = total frequency
9
Q
Percentile of grouped data
A
l + ((kn - cf) / f) (i)
where: k = i / 100 i = percentile term n = total frequency
