Statistics Assignment Comsats Vehari

1. Ishfaq-Arif
(BSSE)
COMSATS INSTITUTE OF TECHNOLOGY VEHARI CAMPUS
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2. Mean:
SUMMING UP ALL THE OBSERVATION AND DIVIDING BY
NUMBER OF OBSERVATIONS. MEAN OF 20, 30, 40 IS
(20+30+40)/3 = 30.
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3. Population mean:
SAMPLE MEAN:
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4. The middle value in an ordered sequence of observations.
That is, to find the median we need to order the data set and
then find the middle value. In case of an even number of
observations the average of the two middle most values is the
median. For example, to find the median of {9, 3, 6, 7, 5}, we
first sort the data giving {3, 5, 6, 7, 9}, then choose the middle
value 6. If the number of observations is even, e.g., {9, 3, 6, 7,
5, 2}, then the median is the average of the two middle values
from the sorted sequence, in this case, (5 + 6) / 2 = 5.5.
MEDIAN: (MIDDLE)
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5. Examples : Odd Number of Elements
Data Set = 2, 5, 9, 3, 5, 4, 7
Reordered = 2, 3, 4, 5, 6, 7, 9
^
Median = 5
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6. Examples : Even Number of Elements
Data Set = 2, 5, 9, 3, 5, 4
Reordered = 2, 3, 4, 5, 5, 9
^ ^
Median = ( 4 + 5 ) / 2 = 4.5
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7. Mode : (most often)
The "Mode" for a data set is the
element that occurs the most often.
It is not uncommon for a data set to
have more than one mode.
This happens when two or more
elements occur with equal frequency
in the data set.
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8. Examples
a) 5.40 1.10 0.42 0.73 0.48 1.10
b) 27 27 27 55 55 55 88 88 99
c) 1 2 3 6 7 8 9 10
 Mode is 1.10
 Bimodal - 27 & 55
 No Mode
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