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Class 11: Statistics – Exercise 32.1

Question 1: Calculate the mean Deviation about the median of the following observations:

(i) 3011, 2780, 3020, 2354, 3541, 4150, 5000

(ii) 38, 70, 48, 34, 42, 55, 63, 46, 54, 44

(iii) 34, 66, 30, 38, 44, 50, 40, 60, 42, 51

(iv) 22, 24, 30, 27, 29, 31, 25, 28, 41, 42

(v) 38, 79, 48, 34, 63, 42, 55, 44, 53, 47

Answer:

(i) 3011, 2780, 3020, 2354, 3541, 4150, 5000

3011 9
2780 240
3020 0
2354 666
3541 521
4150 1130
5000 1980

Total

4546

(ii) 38, 70, 48, 34, 42, 55, 63, 46, 54, 44

38 9
70 23
48 1
34 13
42 5
55 8
63 16
46 1
54 7
44 3
Total 86

(iii) 34, 66, 30, 38, 44, 50, 40, 60, 42, 51

34 9
66 23
30 13
38 5
44 1
50 7
40 3
60 17
42 1
51 8
Total 87

(iv) 22, 24, 30, 27, 29, 31, 25, 28, 41, 42

22 6.5
24 4.5
30 1.5
27 1.5
29 0.5
31 2.5
25 3.5
28 0.5
41 12.5
42 13.5
Total 47

(v) 38, 79, 48, 34, 63, 42, 55, 44, 53, 47

38 9.5
70 22.5
48 0.5
34 13.5
63 15.5
42 5.5
55 7.5
44 3.5
53 5.5
47 0.5
Total 84

Question 2: Calculate the mean deviation about the mean of the following observations:

(i) 4, 7, 8, 9, 10, 12, 13, 17

(ii) 13, 17, 16, 14, 11, 13, 10, 16, 11, 18, 12, 17

(iii) 38, 70, 48, 40, 42, 55, 63, 46, 54, 44

(iv) 36, 72, 46, 42, 60, 45, 53, 46, 51, 49

(v) 57, 64, 43, 67, 49, 59, 44, 47, 61, 59

Answer:

(i) 4, 7, 8, 9, 10, 12, 13, 17

4 6
7 3
8 2
9 1
10 0
12 2
13 3
17 7
Total 24

(ii) 13, 17, 16, 14, 11, 13, 10, 16, 11, 18, 12, 17

13 1
17 3
16 2
14 0
11 3
13 1
10 4
16 2
11 3
18 4
12 2
17 3

Total

28

(iii) 38, 70, 48, 40, 42, 55, 63, 46, 54, 44

38 12
70 20
48 2
40 10
42 8
55 5
63 13
46 4
54 4
44 6

Total

84

(iv) 36, 72, 46, 42, 60, 45, 53, 46, 51, 49

36 14
72 22
46 4
42 8
60 10
45 5
53 3
46 4
51 1
49 1

Total

72

(v) 57, 64, 43, 67, 49, 59, 44, 47, 61, 59

57 2
64 9
43 12
67 12
49 6
59 4
44 11
47 8
61 6
59 4

Total

74

Question 3: Calculate the mean deviation of the following income groups of fine and seven members from their medians:

I Income in Rs.  II Income in Rs.
4000 300
4200 4000
4400 4200
4600 4400
4800 4600
4800
5800

Answer:

1st Data Set

4000 400
4200 200
4400 0
4600 200
4800 400

Total

1200

2nd Data Set

300 4100
4000 400
4200 200
4400 0
4600 200
4800 400
5800 1400

Total

6700

Question 4: The lengths (in cm) of 10 rods in a shop are given below:

40.0, 52.3, 55.2, 72.9, 52.8, 79.0, 32.5, 15.2, 27.9, 30.2

(i) Find the mean deviation from median

(ii) Find mean deviation from the mean also.

Answer:

40 6.15
52.3 6.15
55.2 9.05
72.9 26.75
52.8 6.65
79 32.85
32.5 13.65
15.2 30.95
29.9 18.25
30.2 15.95
Total 166.4

40 5.98
52.3 6.32
55.2 9.22
72.9 26.92
52.8 6.82
79 33.02
32.5 13.48
15.2 30.78
27.9 18.08
32 13.98

Total

164.6

Question 5: In question 1 (iii), (iv), (v) find the number of observations lying between and , where M.D. is the mean deviation from the mean.

Answer:

34 11.5
66 20.5
30 15.5
38 7.5
44 1.5
50 4.5
40 5.5
60 14.5
42 3.5
51 5.5

Total

90

Also

Hence there are 6 observations between 36.5 and 54.5.

22 7.9
24 5.9
30 0.1
27 2.9
29 0.9
31 1.1
25 4.9
28 1.9
41 11.9
42 12.1

Total

48.8

Also

Hence there are 5 observations between 25.02 and 34.78.

38 11.4
70 20.6
48 1.4
34 15.4
63 13.6
42 7.4
55 5.6
44 5.4
53 3.6
47 2.4

Total



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Class 11: Statistics – Exercise 32.1

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