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# Histograms

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#### notes

Study the following example to know about a histogram and how to draw it.

Ex : The table below shows the net asset value (NAV) per unit of mutual funds of some companies. Draw a histogram representing the information.

 NAV (Rs.) 8-9 10-11 12-13 14-15 16-17 No. of mutual funds 20 40 30 25 15

Solution : The given classes are not continuous. Lets make the classes continuous.

 Continuous Classes 7.5-9.5 9.5-11.5 11.5-13.5 13.5-15.5 15.5-17.5 Frequency 20 40 30 25 15

Method of drawing a histogram :
1. If the given classes are not continuous, make them continuous. Such classes are called extended class intervals.
2. Show the classes on the X- axis with a proper scale.
3. Show the frequencies of the Y- axis with a proper scale.
4. Taking each class as the base, draw rectangles with heights proportional to the frequencies.

Note :
On the X-axis, a mark krink is called the krink mark and it is shown between the origin and the first class. It means, there are no observations upto the first class. The mark can be used on the Y- axis also, if needed. This enables us to draw a graph of optimum size.

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Histograms [00:08:37]
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