Mathematics
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 | 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 ?
Statistics
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Answer
By formula,
Class mark =
We will use direct method for solving the mean of the above data as the numerical values of xi and fi are small.
| Number of plants | Number of houses (fi) | Class mark (xi) | fi xi |
|---|---|---|---|
| 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 |
By formula,
Mean = = 8.1
Hence, mean number of plants in each house = 8.1
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