Mathematics
The class mark and frequency of a data is given in the graph. From the graph, Find:
(a) the table showing the class interval and frequency.
(b) the mean
Statistics
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Answer
(a) Class marks : 13, 15, 17, 19, 21, 23.
Difference between two consecutive class marks = 15 - 13 = 2.
Lower limit of class = Class mark - 1
Upper limit of class = Class mark + 1
| Class | Frequency |
|---|---|
| 12 - 14 | 8 |
| 14 - 16 | 2 |
| 16 - 18 | 3 |
| 18 - 20 | 4 |
| 20 - 22 | 5 |
| 22 - 24 | 6 |
(b)
| Class | Class mark (x) | Frequency (f) | fx |
|---|---|---|---|
| 12 - 14 | 13 | 8 | 104 |
| 14 - 16 | 15 | 2 | 30 |
| 16 - 18 | 17 | 3 | 51 |
| 18 - 20 | 19 | 4 | 76 |
| 20 - 22 | 21 | 5 | 105 |
| 22 - 24 | 23 | 6 | 138 |
| Total | Σf = 28 | Σfx = 504 |
Mean = = 18.
Hence, mean = 18.
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