stast 27

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This series is compiled from various resources on net. I have made changes wherever necessary to make it simple to understand. )

Ex 1
The marks secured by 60 students of a class are given below

46, 57, 23,5,12 53, 38,58,26,43
36, 63,26,48,76 45, 66,74,16,86
56, 31,58,90,32 43, 36,66,46,58
36, 59,54,48,21 36, 64,58,45,76
58, 84,68,65,59 74, 48,64,58,50
46, 53,64,57,65 58, 95,56,66,44

Construct a frequency distribution table.

Marks obtained are divided into 10 groups or intervals as follows:

Marks below 10, between 11 and 20, between 11 and 30, and so on, between 91 and 100. Represent each mark by a tally (/), for example, corresponding to the mark 46 we put a tally (/) in the group 41 to 50: similarly we continue putting tallies for each mark. We continue up to four tallies and the fifth tally is put crosswise (\) so that it becomes clear at once that the lot contains five tallies, i. e. there are five marks. A gap is left after a lot of five tallies, before starting again to mark the tallies after each lot. The number of tallies in a class or group indicates the number of marks falling under that group. This number is known as the frequency of that group or corresponding to that class interval. Proceeding in this way, we get the following frequency table.