Mathematics
If the mean of the following distribution is 24, find the value of a :
| Marks | Number of students |
|---|---|
| 0 - 10 | 7 |
| 10 - 20 | a |
| 20 - 30 | 8 |
| 30 - 40 | 10 |
| 40 - 50 | 5 |
Measures of Central Tendency
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Answer
We construct the following table :
| Marks (Classes) | Class mark (yi) | Number of students (Frequency (fi)) | fiyi |
|---|---|---|---|
| 0 - 10 | 5 | 7 | 35 |
| 10 - 20 | 15 | a | 15a |
| 20 - 30 | 25 | 8 | 200 |
| 30 - 40 | 35 | 10 | 350 |
| 40 - 50 | 45 | 5 | 225 |
| Total | 30 + a | 810 + 15a |
Hence, the value of a = 10.
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