. Find the mean of the following distribution
Class: Frequency:
3 - 5 5
5 - 7 10
7 - 9 10
9 - 11 7
11 - 13 8
Best Answer
Explanation:
Firstly, construct a table with the four columns: class interval, frequency, mid-value and FX.
| Class interval | Frequency (f) |
| 3-5 | 5 |
| 5-7 | 10 |
| 7-9 | 10 |
| 9-11 | 7 |
| 11-13 | 8 |
Then, compute the middle value for each of the class intervals, by adding the lower and upper limit of the class interval and then dividing the resultant figure by 2.
Then construct the FX column, and for each observation multiply the respective frequency with the middle value.
Make a total of the frequency and fx columns.
| Class interval | Frequency (f) | Middle value (X) | FX (f*X) |
| 3-5 | 5 | 4 | 20 |
| 5-7 | 10 | 6 | 60 |
| 7-9 | 10 | 8 | 80 |
| 9*11 | 7 | 10 | 70 |
| 11-13 | 8 | 12 | 96 |
| Total (Σ) | 40 | 326 |
The mean is:
Final answer:
The mean of the distribution is 8.15
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