Download Important Formulas Chapters 1 and 2

Important Formulas Chapters 1 and 2
class width =
range of data
number of classes
Formula for the midpoint:
lower class lim it
midpo int
weighted mean:
x w
x
w
upper class lim it
2
mean for individual data:
x
x
x
n
N
mean for grouped data:
xm f
x
n
Formulas for the variance:
Range:
2
Formula for the
2
x
s
N
lowest value
x x
2
2
R = highest value –
n 1
Formulas for the standard deviation:
2
x
s
N
x
x
2
n 1
Formula for the variance for grouped data:
s
x
2
x f
n 1
Formula for the z score (standard score):
x
z
z
x
x
s