RD Sharma Solutions Chapter 7 Statistics Exercise 7.3 Class 10 Maths
Chapter Name  RD Sharma Chapter 7 Statistics 
Book Name  RD Sharma Mathematics for Class 10 
Other Exercises 

Related Study  NCERT Solutions for Class 10 Maths 
Exercise 7.3 Solutions
1. The following table gives the distribution of total household expenditure(in rupees) of manual workers in a city.
Expenditure (in rupees)(x) 
Frequency (f_{i}) 
Expenditure (in rupees)(x_{i}) 
Frequency(f_{i}) 
100 – 150 
24 
300 – 350 
30 
150 – 200 
40 
350 400 
22 
200 – 250 
33 
400 – 450 
16 
250 – 300 
28 
450 500 
7 
Find the average expenditure (in rupees) per household.
Solution
Let the assumed mean (A) = 275.
2. A survey was conducted by a group of students as a part of their environment awareness program, in which they collected the following data regarding the number of plants in 20 houses in a locality. Find the mean number of plants per house.
Number of plants: 
0 – 2 
2 – 4 
4 – 6 
6 – 8 
8 – 10 
10 – 12 
12 – 14 
Number of houses : 
1 
2 
1 
5 
6 
2 
3 
Which method did you use for finding the mean, and why ?
Solution
Daily wages(in Rs.) 
100 – 120 
120 – 140 
140 – 160 
160 – 180 
180 – 200 
Number of workers : 
12 
14 
8 
6 
10 
Find the mean dialy wages of the workers of the factory by using an appropriate method.
Solution
Let the assume mean (A) = 150
4. Thirty women were examined in a hospital by a doctor and the number of heart beats per minute recorded and summarized as follows. Find the mean heart beats per minute for these women, choosing a suitable method.
Number of heat 
65 – 68 
68 – 71 
71 – 74 
74 – 77 
77 – 80 
80 – 83 
83 – 86 
Number of women: 
2 
4 
3 
8 
7 
4 
2 
Solution
Class interval : 
0 – 6 
6 – 12 
12 – 18 
18 – 24 
24 – 30 
Frequency: 
6 
8 
10 
9 
7 
Solution
6.
Class interval: 
50 – 70 
70 – 90 
90 – 110 
110 – 130 
130 – 150 
150 – 170 
Frequency: 
18 
12 
13 
27 
8 
22 
Solution
7.
Class interval: 
0 – 8 
8 – 16 
16 – 24 
24 – 32 
32 – 40 
Frequency: 
6 
7 
10 
8 
9 
Solution
8.
Class interval: 
0 – 6 
6 – 12 
12 – 18 
18 – 24 
24 – 30 
Frequency : 
7 
5 
10 
12 
6 
Solution
9.
Class interval : 
0 – 10 
10 – 20 
20 – 30 
30 – 40 
40 – 50 
Frequency: 
9 
12 
15 
10 
14 
Solution
10.
Class interval : 
0 – 8 
8 – 16 
16 – 24 
24 – 32 
32 – 40 
Frequency: 
5 
9 
10 
8 
8 
Solution
11.
Class interval: 
0 – 8 
8 – 16 
16 – 24 
24 – 32 
32 – 40 
Frequency: 
5 
6 
4 
3 
2 
Solution
12.
Class interval: 
10 – 30 
30 – 50 
50 – 70 
70 – 90 
90 – 110 
110 – 130 
Frequency: 
5 
8 
12 
20 
3 
2 
Solution
13.
Class interval: 
25 – 35 
35 – 45 
45 – 55 
55 – 65 
65 – 75 
Frequency: 
6 
10 
8 
12 
4 
Solution
14.
Classes: 
25 – 29 
30 – 34 
35 – 39 
40 – 44 
45 – 49 
50 – 54 
55 – 59 
Frequency: 
14 
22 
16 
6 
5 
3 
4 
Solution
Size of item: 
1 4 
4 – 9 
9 – 16 
16 – 27 
Frequency: 
6 
12 
26 
20 
Solution
16. The weekly observations on cost of living index in a certain city for the year 2004 – 2005 are given below. Compute the weekly cost of living index.
Cost of living index 
Number of Students 
Cost of living index 
Number of Students 
1400 – 1500 
5 
1700 – 1800 
9 
1500 – 1600 
10 
1800 – 1900 
6 
1600  1700 
20 
1900 – 2000 
2 
Solution
Marks: 
0 – 10 
10 – 20 
20 – 30 
30 – 40 
40 – 50 
Number of students : 
20 
24 
40 
36 
20 
Calculate the average marks by using all the three methods: direct method, assumed mean deviation and shortcut method.
Solution
Class: 
0 – 20 
20 – 40 
40 – 60 
60 – 80 
80 – 100 
100 – 120 
Frequency: 
5 
F_{1} 
10 
F_{2} 
7 
8 
Solution
Class interval: 
11 – 13 
13 – 15 
15 – 17 
17 – 19 
19 – 21 
21 – 23 
23 – 25 
Frequency: 
7 
6 
9 
13 
 
5 
4 
Solution
Class : 
0 – 10 
10 – 20 
20 – 30 
30 – 40 
40 – 50 
Frequency: 
8 
P 
12 
13 
10 
Solution
Number of mangoes: 
50 – 52 
53 – 55 
56 – 58 
59 61 
62 64 
Number of boxes: 
15 
110 
135 
115 
25 
Solution
Daily expenditure(in Rs): 
100 – 150 
150 – 200 
200 – 250 
250 – 300 
300 – 350 
Number of households: 
4 
5 
12 
2 
2 
Find the mean daily expenditure on food by a suitable method.
Solution
Concentration fo SO_{2} (in ppm) 
Frequency 
0.00 – 0.04 
4 
0.04 – 0.08 
9 
0.08 – 0.12 
9 
0.12 – 0.16 
2 
0.16 – 0.20 
4 
0.20 – 0.24 
2 
Find the mean concentration of SO_{2} in the air.
Solution
Number of days: 
0 – 6 
6 – 10 
10 – 14 
14 – 20 
20 – 28 
28 – 38 
38 – 40 
Number of students: 
11 
10 
7 
4 
4 
3 
1 
Solution
We may find class mark of each interval by using the relation
So, mean number of days is 12, 38 days for which student was absent.
25. The following table gives the literacy rate(in percentage) of 35 cities. Find the mean literacy rate.
Literacy rate(in %): 
45 – 55 
55 – 65 
65 – 75 
75 – 85 
85 – 95 
Number of cities: 
3 
10 
11 
8 
3 
Solution