Find the mean deviation about the mean for the data
4, 7, 8, 9, 10, 12, 13, 17
Answer :
The given data is
4, 7, 8, 9, 10, 12, 13, 17
Mean of the data,
The deviations of the respective observations from the mean are
â€“6, â€“ 3, â€“2, â€“1, 0, 2, 3, 7
The absolute values of the deviations, i.e., are
6, 3, 2, 1, 0, 2, 3, 7
The required mean deviation about the mean is
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Find the mean deviation about the mean for the data
38, 70, 48, 40, 42, 55, 63, 46, 54, 44
Answer :
The given data is
38, 70, 48, 40, 42, 55, 63, 46, 54, 44
Mean of the given data,
The deviations of the respective observations from the mean are
â€“12, 20, â€“2, â€“10, â€“8, 5, 13, â€“4, 4, â€“6
The absolute values of the deviations, i.e. , are
12, 20, 2, 10, 8, 5, 13, 4, 4, 6
The required mean deviation about the mean is
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Find the mean deviation about the median for the data.
13, 17, 16, 14, 11, 13, 10, 16, 11, 18, 12, 17
Answer :
Find the mean deviation about the median for the data
36, 72, 46, 42, 60, 45, 53, 46, 51, 49
Answer :
Find the mean deviation about the mean for the data.
x_{i} 
5 
10 
15 
20 
25 
f_{i} 
7 
4 
6 
3 
5 
Answer :
Find the mean deviation about the mean for the data
x_{i} 
10 
30 
50 
70 
90 
f_{i} 
4 
24 
28 
16 
8 
Answer :
Find the mean deviation about the median for the data.
x_{i} 
5 
7 
9 
10 
12 
15 
f_{i} 
8 
6 
2 
2 
2 
6 
Answer :
Find the mean deviation about the median for the data
x_{i} 
15 
21 
27 
30 
35 
f_{i} 
3 
5 
6 
7 
8 
Answer :
Find the mean deviation about the mean for the data.
Income per day 
Number of persons 
0100 
4 
100200 
8 
200300 
9 
300400 
10 
400500 
7 
500600 
5 
600700 
4 
700800 
3 
Answer :
Find the mean deviation about the mean for the data
Height in cms 
Number of boys 
95105 
9 
105115 
13 
115125 
26 
125135 
30 
135145 
12 
145155 
10 
Answer :
Calculate the mean deviation about median age for the age distribution of 100 persons given below:
Age 
Number 
1620 
5 
2125 
6 
2630 
12 
3135 
14 
3640 
26 
4145 
12 
4650 
16 
5155 
9 
Answer :
Find the mean and variance for the data 6, 7, 10, 12, 13, 4, 8, 12
Answer :
Find the mean and variance for the first n natural numbers
Answer :
Find the mean and variance for the first 10 multiples of 3
Answer :
Find the mean and variance for the data
xi 
6 
10 
14 
18 
24 
28 
30 
f i 
2 
4 
7 
12 
8 
4 
3 
Answer :
Find the mean and variance for the data
xi 
92 
93 
97 
98 
102 
104 
109 
f i 
3 
2 
3 
2 
6 
3 
3 
Answer :
Find the mean and standard deviation using shortcut method.
x_{i} 
60 
61 
62 
63 
64 
65 
66 
67 
68 
f_{i} 
2 
1 
12 
29 
25 
12 
10 
4 
5 
Answer :
Find the mean and variance for the following frequency distribution.
Classes 
030 
3060 
6090 
90120 
120150 
150180 
180210 
Frequencies 
2 
3 
5 
10 
3 
5 
2 
Answer :
Find the mean and variance for the following frequency distribution.
Classes 
010 
1020 
2030 
3040 
4050 
Frequencies 
5 
8 
15 
16 
6 
Answer :
Find the mean, variance and standard deviation using shortcut method
Height in cms 
No. of children 
7075 
3 
7580 
4 
8085 
7 
8590 
7 
9095 
15 
95100 
9 
100105 
6 
105110 
6 
110115 
3 
Answer :
The diameters of circles (in mm) drawn in a design are given below:
Diameters 
No. of children 
3336 
15 
3740 
17 
4144 
21 
4548 
22 
4952 
25 
Answer :
From the data given below state which group is more variable, A or B?
Marks 
1020 
2030 
3040 
4050 
5060 
6070 
7080 
Group A 
9 
17 
32 
33 
40 
10 
9 
Group B 
10 
20 
30 
25 
43 
15 
7 
Answer :
From the data given below state which group is more variable, A or B?
Marks 
1020 
2030 
3040 
4050 
5060 
6070 
7080 
Group A 
9 
17 
32 
33 
40 
10 
9 
Group B 
10 
20 
30 
25 
43 
15 
7 
Answer :
From the prices of shares X and Y below, find out which is more stable in value:
X 
35 
54 
52 
53 
56 
58 
52 
50 
51 
49 
Y 
108 
107 
105 
105 
106 
107 
104 
103 
104 
101 
Answer :
An analysis of monthly wages paid to workers in two firms A and B, belonging to the same industry, gives the following results:
Firm A 
Firm B 

No. of wage earners 
586 
648 
Mean of monthly wages 
Rs 5253 
Rs 5253 
Variance of the distribution of wages 
100 
121 
(i) Which firm A or B pays larger amount as monthly wages?
(ii) Which firm, A or B, shows greater variability in individual wages?
Answer :
The following is the record of goals scored by team A in a football session:
No. of goals scored 
0 
1 
2 
3 
4 
No. of matches 
1 
9 
7 
5 
3 
For the team B, mean number of goals scored per match was 2 with a standard
deviation 1.25 goals. Find which team may be considered more consistent?
Answer :
The sum and sum of squares corresponding to length x (in cm) and weight y
(in gm) of 50 plant products are given below:
Which is more varying, the length or weight?
Answer :
The mean and variance of eight observations are 9 and 9.25, respectively. If six of the observations are 6, 7, 10, 12, 12 and 13, find the remaining two observations.
Answer :
The mean and variance of 7 observations are 8 and 16, respectively. If five of the observations are 2, 4, 10, 12 and 14. Find the remaining two observations.
Answer :
The mean and standard deviation of six observations are 8 and 4, respectively. If each observation is multiplied by 3, find the new mean and new standard deviation of the resulting observations.
Answer :
Given that is the mean and Ïƒ^{2} is the variance of n observations x_{1}, x_{2} â€¦ x_{n}. Prove that the mean and variance of the observations ax_{1}, ax_{2}, ax_{3} â€¦ax_{n} are and a^{2} Ïƒ^{2}, respectively (a ≠ 0).
Answer :
The mean and standard deviation of 20 observations are found to be 10 and 2, respectively. On rechecking, it was found that an observation 8 was incorrect. Calculate the correct mean and standard deviation in each of the following cases:
(i) If wrong item is omitted.
(ii) If it is replaced by 12.
Answer :
The mean and standard deviation of marks obtained by 50 students of a class in three subjects, Mathematics, Physics and Chemistry are given below:
Subject 
Mathematics 
Physics 
Chemistry 
Mean 
42 
32 
40.9 
Standard deviation 
12 
15 
20 
Which of the three subjects shows the highest variability in
marks and which shows the lowest?
Answer :
The mean and standard deviation of a group of 100 observations were found to be 20 and 3, respectively. Later on it was found that three observations were incorrect, which were recorded as 21, 21 and 18. Find the mean and standard deviation if the incorrect observations are omitted.
Answer :
Maths  Maths : CBSE NCERT Exercise Solutions for Class 11th for Statistics ( Exercise 15.1, 15.2, 15.3, miscellaneous ) will be available online in PDF book form soon. The solutions are absolutely Free. Soon you will be able to download the solutions.
Exercise 15.1 
Question 1 
Question 2 
Question 3 
Question 4 
Question 5 
Question 6 
Question 7 
Question 8 
Question 9 
Question 10 
Question 11 
Exercise 15.2 
Question 1 
Question 2 
Question 3 
Question 4 
Question 5 
Question 6 
Question 7 
Question 8 
Question 9 
Question 10 
Exercise 15.3 
Question 1 
Question 2 
Question 3 
Question 4 
Question 5 
Question 6 
Exercise Miscellaneous 
Question 1 
Question 2 
Question 3 
Question 4 
Question 5 
Question 6 
Question 7 