# Ex.14.2 Q1 Statistics Solution - NCERT Maths Class 9

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## Question

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.

Reasoning:

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

Steps:

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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