Write the median class for the following frequency distribution:
Class-interval: | 0-10 | 10-20 | 20-30 | 30-40 | 40-50 | 50-60 | 60-70 | 70-80 |
Frequency: | 5 | 8 | 7 | 12 | 28 | 20 | 10 | 10 |
First, we prepare the cumulative frequency table for above data
Class | Frequency | Cumulative Frequency |
0-10 10-20 20-30 30-40 40-50 50-60 60-70 70-80 | 5 8 7 12 28 20 10 10 | 5 13 20 32 60 80 90 100 |
N = 100 |
We know that median class of a data is the class-interval corresponding to cumulative frequency just greater than 
Where,
N = sum of all frequencies
As N = 100 therefore 
And
Cumulative frequency just greater than 50 is 60 which lies corresponding to class 40-50
Hence, 40-50 is median class.
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