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Description
- Computation of Measures of Central Tendency - Mean
- Direct Method of Mean
- Assumed Mean Method Or Shift of Origine Method
- Step Deviation Method for Mean Or Shift of Origin and Change of Scale
- Assumed Mean Method, Step-deviation method
Questions
The table below shows the daily expenditure on food of 25 households in a locality.
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.
In a retail market, fruit vendors 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.
Number of mangoe | 50 − 52 | 53 − 55 | 56 − 58 | 59 − 61 | 62 − 64 |
Number of boxes | 15 | 110 | 135 | 115 | 25 |
Find the mean number of mangoes kept in a packing box. Which method of finding the mean did you choose?
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 |
Number of workers | 7 | 6 | 9 | 13 | f | 5 | 4 |
To find out the concentration of SO_{2} 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 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.
Consider the following distribution of daily wages of 50 worker of a factory.
Daily wages (in Rs) |
100 − 120 |
120 − 140 |
140 −1 60 |
160 − 180 |
180 − 200 |
Number of workers |
12 |
14 |
8 |
6 |
10 |
Find the mean daily wages of the workers of the factory by using an appropriate method.
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 |
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 |
Thirty women were examined in a hospital by a doctor and the number of heart beats per minute were recorded and summarized as follows. Fine 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 |
A survey was conducted by a group of students as a part of their environment awareness programme, 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?
The following table gives the frequency distribution of trees planted by different Housing Societies in a particular locality:
No. of Trees | No. of Housing Societies |
10-15 | 2 |
15-20 | 7 |
20-25 | 9 |
25-30 | 8 |
30-35 | 6 |
35-40 | 4 |
Find the mean number of trees planted by Housing Societies by using ‘Assumed Means Method’
The measurements (in mm) of the diameters of the head of the screws are given below:
Diameter (in mm) | No. of Screws |
33 — 35 | 10 |
36 — 38 | 19 |
39 — 41 | 23 |
42 — 44 | 21 |
45 — 47 | 27 |
Calculate mean diameter of head of a screw by ‘Assumed Mean Method’.