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Question
Below is the given frequency distribution of words in an essay:
| Number of words | Number of Candidates |
| 600 - 800 | 12 |
| 800 - 1000 | 14 |
| 1000 - 1200 | 40 |
| 1200 - 1400 | 15 |
| 1400 - 1600 | 19 |
Find the mean number of words written.
Solution
| No. of words | Class Mark | No. of candidate | fx |
| x | f | fx | |
| 600 - 800 | 700 | 12 | 8400 |
| 800 - 1000 | 900 | 14 | 12600 |
| 1000 - 1200 | 1100 | 40 | 44000 |
| 1200 - 1400 | 1300 | 15 | 19500 |
| 1400 - 1600 | 1500 | 19 | 28500 |
| ∑f =100 | ∑fx = 113000 |
Mean by Direct method
Mean `(bar("x")) = (∑"f""x")/(∑"f") =113000/100`
= 1130 words
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