Explain the meaning of the following term:

Class interval

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Class size

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Class mark

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Class limit

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True class limits

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Frequency of a class

Explain the meaning of the following term:

Cumulative frequency of a class.

The blood groups of$30$ students of a class are recorded as under:

$A, B, O, O, AB, O, A, O, A, B, O, B, A, O, O, A, AB, O, A, A, O, O, AB, B, A, O, B, A, B, O$.

Represent this data in the form of a frequency distribution table.

The blood groups of$30$ students of a class more than its complement.

$A, B, O, O, AB, O, A, O, A, B, O, B, A, O, O, A, AB, O, A, A, O, O, AB, B, A, O, B, A, B, O$

Find out which is the most common and which is the rarest blood group among these students.