Page 14 - Math SL HB Sem 3

Cumulative FrequencY graPh:
We can conslruct a cumulative frequency table from the frequency distribution

\. Example:

Height of students Upper class Number of Cumulahve The mulative frequencY
is the total frequency
lcml bou nd a ry students freq uency up to a particular class
< 155 155 2 boundary or a value
155< lL< 160 160 6 8 (i.e. t Llnning total).
160<h<165 165 10 18
This must be the tobl
]65<h<770 L70 7 25 population of students,
t70<h<L75 175 la
775<h<7ao 180 1 29
180<h<185 185 r 30
A cumulative frequency graph can then be plotted with cumulalive frequencies (c.f.) against
the upper class boundaries:

A cumulative frequenry graph showing the heights of a troup
of people

35

30

! I
25
Cumulative
20
frequency
I ++
-t-t-++- - 1,. -t-
-+-FfF
15
10

5

0
150 1s5 160 165 770 L75 180 185 190
Height/cm

f,

$ Notice:
The steeper the slope of the cumulative frequency polygon, the greater the change of frequency
over the variable h.

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