Ex.14.2 Q1 Statistics Solution - NCERT Maths Class 9

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The blood groups of \(30\) students of Class VIII are recorded as follows:

\(A,\, B,\, O,\, O,\, AB,\, O,\, A,\, O,\, B,\, A,\, O,\, B,\, A,\, O,\, O,\\ A,\, AB,\, O,\, A,\, A,\, O,\, O,\, AB,\, B,\, A,\, O,\, B,\, A,\, B,\, O.\)

Represent this data in the form of a frequency distribution table. Which is the most common, and which is the rarest, blood group among these students?

Text Solution


What is known?

The blood group of \(30\) students of class VIII.

What is unknown?

The most common blood group and the rarest blood group.


By drawing frequency distribution table, we can check which group is occurring most and which group is occurring least time.


Let us sort the data using a table so as to make the data more easily understandable and its important features visible.

This table is known as frequency distribution table.

‘Frequency’ of a particular data refer to the number of times the data value occurs.

In our case frequency refer to the number of students having the same blood group.

\(\therefore\) The blood group of \(30\) students can be shown as follows:

Blood Group No of Students(frequency)
\(A\) \(9\)
\(B\) \(6\)
\(O\) \(12\)
\(AB\) \(3\)
Total \(30\)

So we can see easily now, from the table that:

  • The most common (the most frequently occurring) blood group is ‘\(O\)’.
  • The rarest blood group (least frequently occurring) is ‘\(AB\)’.
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