Page 28 - Basic Statistics

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d 1
Mode : Mod = L + . W
d 1 + d 2

Worked Example 2.4 :

Calculate the mean, median, and mode for grouped data in Table 6

Worked Solution :

5 + 60 + . . . + 290 1.525
Mean : X = = = 27.7273
55 55

Median class is the class that contains the value that lies in the middle of

the data, ie (n / 2)th observation, with n / 2 = 55/2 = 27.5.

In Table 6 the cumulative frequency column, from the first class to 2nd

class, there are 8 observations, and until the 3rd class has been there are 28

observations. This means that the 27.5th data falls in the 3rd class, which is the
class interval "15 - <25". This the 3rd class a median class has a lower limit of 15

and a frequency of 20.

f c
Median : Md = L + . W
f m

 27 8 - 5 .   19.5 
Median : Md = 15 +  .  10 = 15 +   10 = 24.75
 20   20 

d 1
Mode : Mod = L + . W
d 1 + d 2

( 20 ) 6 −
Modus : Mod = 15 + . 10
( 20 ) 6 - ( + 20 - 15 )

14
= 15 + . 10 = 22.07
14 + 5

~~* CHAPTER 2 NUMERICAL MEASURES TO SUMMARIZE DATA *~~