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STATISTICS

Is the study or the methods of collecting, summarizing and presenting data and interpreting the information.
MEASURES OF CENTRAL TENDENCY
1. Mean
2. Median
3. Mode

MEAN “X”
Is obtained by adding up all the data values then divide by the number of characters.
I.e.
i.e. =mean
x1+x2+x3………. Sum of observations
N =number of observation

Example
1. Find mean score from the following scores of biology test 10, 25, 45, 15,63 42,7
=
= 29.57

When the data is given with frequency or in grouped data;
= or
f= frequency
∑= summation

2. Find the mean number of children per family from the following table
No. of children [x]
0
1
2
3
4
5
6
7
8
No. of families [f]
3
6
7
8
10
12
8
4
2

Solution

Finding the mean of the numbers in the table below;
No. of children [x]
No. of families [f]
fx

0
3
0
1
6
6
2
7
14
3
8
24
4
10
40
5
12
60
6
8
48
7
4
28
8
2
16
Total
60
236












= =

= 3.93

Exercise
Class interval
Class mark [x]
Frequency [f]
fx
91-95
93
0
0
86-90
88
1
88
81-85
83
6
498
76-80
78
10
780

71-75
73
15
1095
66-70
68
34
2312
61-65
63
22
1386
56-60
58
10
580
51-55
53
2
106
N=100
∑fx=6845
Class interval
Class mark[x]
F
D=x-A
fd
91-95
93
0
35
0
86-90
88
1
30
30
81-85
83
6
25
150
76-80
78
10
20
200
71-75
73
15
15
225
66-70
68
34
10
340
61-65
63

22
5
110
56-60
58
10
0
0
51-55
53
2
-5
-10
Total
100

1045

Class mark[x]
f
fx
61
10
610
64
20
1280
67
30
2010
70
15
1050
73
5
365
Total
80
5315
Class mark

frequency
41-46
3
35-40
4
29-34
9
23-28
12
17-22
18
11-16
28
5-10
26
Class mark[x]
Frequency [f]
D= x-A
fd
41-46
3
30
90
35-40

4
24
96
29-34
9
18
162
23-28
12
12
144
17-22
18
6
108
11-16
28
0
0
5-10
26
-6
-156
Total
100
444
Number of visits
frequency
5
16
6
33
1
47
8
54
9
31
10
10
11
4
12
2
13
0
14
2
15
1
Number of visits[x]
Frequency [f]
Fx
5
16
80
6
33
198
7
47
329
8
54
432
9
31
279
10
10
100
11
4
44
12
2
24
13
0
0
14
2
28
15
1
15
Total
200
1529


Length [mm]
f
Cumulative frequency
88-96
3
3
97-105
5
8
106-114
9
17
115-123
12
29
124-132
5
34
133-141
4
38
142-150
2
40
Total
40
169
Marks
frequency
Cumulative frequency
11-20
1
1
21-30
3
4
31-40
10
14
41-50
21
35
51-60
6
41
61-70
5
46
71-80
4
50
50

C:thlbcrtzSTATISTICSf3_filesimage055.gif
Class mark
frequency
Cumulative frequency

92
3
3
101
5
18
119
10
33
128
13
46
137
7
53
Total
53
Class mark
frequency
Cumulative frequency
15
0
0
20

5
5
25
15
20
30
12
32
35
10
42
40
0
42
Height [cm]
160
165
170

175
180
185
frequency
2
12
32
24
21
8
Height in [cm]
frequency
Cumulative frequency

ecolebooks.com
160
3
3
165
12
15
170
32
47
175
24
71
180
21
92
185
8
100
total
100
Class mark
frequency
Cumulative frequency
15.5
1
1
25.5
3
4
35.5
10
14
45.5
21
35
55.5

6
41
65.5
5
46
75.5
4
50
Total
50
Wages in [TSHS}
frequency
Cumulative frequency
55
8
8
65
10

18
75
16
34
85
15
49
95
10
59
105
5
64
Total
64

Mass in kg
frequency
Cumulative frequency
47
0
47
0
0
52
16
16

51
20
36
62
14
50
61
12
62
72
8
70
77
6
76
82
4
80
87
0
80
Total
80
Height in cm
frequency
82
10
85
11
88
14
91
10
94
9
97
6
Total
60


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