HP 50g Graphing Calculator User Manual
Page 575
Page 18-8
to calculate for uniform-size classes (or bins), and the class mark is just the
average of the class boundaries for each class. Finally, the cumulative
frequency is obtained by adding to each value in the last column, except the
first, the frequency in the next row, and replacing the result in the last column of
the next row. Thus, for the second class, the cumulative frequency is 18+15 =
33, while for class number 3, the cumulative frequency is 33 + 16 = 49, and so
on. The cumulative frequency represents the frequency of those numbers that
are smaller than or equal to the upper boundary of any given class.
Given the (column) vector of frequencies generated by the calculator, you can
obtain a cumulative frequency vector by using the following program in RPN
mode:
Class
No.
Class
Bound.
Class
mark.
Frequency
Cumulative
i
XB
i
XB
i+1
Xm
i
f
i
frequency
< XB
1
outlier
below
range
25
1
10
20
15
18
18
2
20
30
25
14
32
3
30
40
35
17
49
4
40
50
45
17
66
5
50
60
55
22
88
6
60
70
65
22
110
7
70
80
75
24
134
k = 8
80
90
85
19
153
>XB
k
outliers
above
range
22