Short Answer Type|
Number of plants |
Number of houses |
|
0-2 |
1 |
|
2-4 |
2 |
|
4-6 |
1 |
|
6-8 |
5 |
|
8-10 |
6 |
|
10-12 |
2 |
|
12-14 |
3 |
Which method did you use for finding the mean and why?
|
Number of plants |
Number of houses (fi) |
Class mark (xi) |
fixi |
|
0-2 |
1 |
1 |
1 |
|
2-4 |
2 |
3 |
6 |
|
4-6 |
1 |
5 |
5 |
|
6-8 |
5 |
7 |
35 |
|
8-10 |
6 |
9 |
54 |
|
10-12 |
2 |
11 |
22 |
|
12-14 |
3 |
13 |
39 |
|
Total |
Σfi = 20 |
Σfixi = 162 |
= 162
Hence, the mean number of plants per house = 8.1
We have used the direct method for finding the mean because numerical values of xiand fi are small.
Consider the following distribution of daily wages of 50 workers of a factory:
|
Daily wages (in Rs.) |
Number of workers |
|
100-120 |
12 |
|
120-140 |
14 |
|
140-160 |
8 |
|
160-180 |
6 |
|
180-200 |
10 |
The following distribution shows the daily pocket allowance of children of a locality. The mean pocket allowance is Rs. 18. Find the missing frequency 'f'.
|
Daily pocket allowance (in Rs.) |
11-13 |
13-15 |
15-17 |
17-19 |
19-21 |
21-23 |
23-25 |
|
No. of childrens |
7 |
6 |
9 |
13 |
f |
5 |
4 |
Thirty women were examined in a hospital by a doctor and the number of heart beats per minute were recorded and summarised as follows. Find the mean heart beats per minute for these women, choosing a suitable method.
|
Number of heart beats per minute |
65-68 |
68-71 |
71-74 |
74-77 |
77-80 |
80-83 |
83-86 |
|
Number of women |
2 |
4 |
3 |
8 |
7 |
4 |
2 |
In a retail market, fruit venders were selling mangoes kept in packing boxes. These boxes contained varying number of mangoes. The following was the distribution of mangoes according to the number of boxes. Find the mean number of mangoes kept in a packing box. Which method of finding the mean did you choose?
|
No. of Mangoes |
50-52 |
53-55 |
56-58 |
59-61 |
62-64 |
|
No. of boxes |
15 |
110 |
135 |
115 |
25 |
The table below shows the daily expenditure on food of 25 household in a locality.
|
Daily Exp. (in Rs.) |
100-150 |
150-200 |
200-250 |
250-300 |
300-350 |
|
No. of house hold |
4 |
5 |
12 |
2 |
2 |
Find the mean daily expenditure on food by a suitable method.
To find out the concentration of SO2 in the air (in parts per million, i.e., ppm), the data was collected for 30 localities in a certain city and is presented below:
|
Concentration of SO2 (in ppm) |
0.00-0.04 |
0.04-0.08 |
0.08-012 |
0.12-0.16 |
0.16-0.20 |
0.20-0.24 |
|
Frequencey |
4 |
9 |
9 |
2 |
4 |
2 |
Find the mean concentration of SO2 in the air.
A class teacher has the following absentee record of 40 students of a class for the whole term. Find the mean number of days a student was absent.
|
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 |
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 |
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