9. The following table gives the literacy rate (in percentage) of 35 cities. Find the mean literacy rate.
8. 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.
7. To find out the concentration of 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:
Find the mean concentration of in the air.
6. The table below shows the daily expenditure on food of 25 households in a locality.
Find the mean daily expenditure on food by a suitable method.
5. 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.
Find the mean number of mangoes kept in a packing box. Which method of finding the mean did you choose?
Let the assumed mean be a = 57
Number of mangoes |
Number of boxes |
Class mark |
||
50-52 | 15 | 51 | -6 | -90 |
53-55 | 110 | 54 | -3 | -330 |
56-58 | 135 | 57 | 0 | 0 |
59-61 | 115 | 60 | 3 | 345 |
62-64 | 25 | 63 | 6 | 150 |
=400 |
=75 |
Mean,
Therefore, the mean number of mangoes kept in a packing box is approx 57.19
4. Thirty women were examined in a hospital by a doctor and the number of heartbeats per minute were recorded and summarised as follows. Find the mean heartbeats per minute for these women, choosing a suitable method.
Let the assumed mean be a = 75.5
No. of heartbeats per minute |
Number of women |
Class mark |
||
65-68 | 2 | 66.5 | -9 | -18 |
68-71 | 4 | 69.5 | -6 | -24 |
71-74 | 3 | 72.5 | -3 | -9 |
74-77 | 8 | 75.5 | 0 | 0 |
77-80 | 7 | 78.5 | 3 | 21 |
80-83 | 4 | 81.5 | 6 | 24 |
83-86 | 2 | 84.5 | 9 | 18 |
=30 |
=12 |
Mean,
Therefore, the mean heartbeats per minute of these women is 75.9
3. following distribution shows the daily pocket allowance of children of a locality. The mean pocket allowance is Rs 18. Find the missing frequency f.
2. Consider the following distribution of daily wages of 50 workers of a factory.
Find the mean daily wages of the workers of the factory by using an appropriate method.
1. 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.
Which method did you use for finding the mean, and why?