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Find the mean of the following distribution :
Class: $30-40, 40-50, 50-60, 60-70, 70-80$
Frequency: $6, 13, 8, 12, 11$
Class: $30-40, 40-50, 50-60, 60-70, 70-80$
Frequency: $6, 13, 8, 12, 11$
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Correct table (2 Marks)
Class | Frequency ($f_i$) | $x_i$ | $f_i x_i$
--- | --- | --- | ---
30-40 | 6 | 35 | 210
40-50 | 13 | 45 | 585
50-60 | 8 | 55 | 440
60-70 | 12 | 65 | 780
70-80 | 11 | 75 | 825
Total | 50 | | 2840
Mean = $\frac{2840}{50} = 56.8$ (1 Mark)
Class | Frequency ($f_i$) | $x_i$ | $f_i x_i$
--- | --- | --- | ---
30-40 | 6 | 35 | 210
40-50 | 13 | 45 | 585
50-60 | 8 | 55 | 440
60-70 | 12 | 65 | 780
70-80 | 11 | 75 | 825
Total | 50 | | 2840
Mean = $\frac{2840}{50} = 56.8$ (1 Mark)