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Question
Compute the mean for following data:
| Class | 1-3 | 3-5 | 5-7 | 7-9 |
| Frequency | 12 | 22 | 27 | 19 |
Solution
The given data is shown as follows:
| Class | Frequency | Class mark `(X_i)` | `f_i X_i` |
| 1-3 | 12 | 2 | 24 |
| 3-5 | 22 | 4 | 88 |
| 5-7 | 27 | 6 | 162 |
| 7-9 | 19 | 8 | 152 |
| Total | ∑ `f_i = 80` | ∑`f_i X_i = 426` |
The mean of given data is given by
x = `( sum_(i) f_i x_i)/(sum_i f_i)`
=`426/80`
=5.325
Thus, the mean of the following data is 5.325.
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