Note: If the divided result is fraction, it must be round up. If it is divisibly devided, the result must always be plus 1.

3.The Class Interval must be written in order from Min-Max, or Max-Min

4. Finding the Frequency of each Class Interval by using mark

Example2: Draw a Frequency Distribution Table by setting the Class Interval width to 5 with belows data. The data is the height of 36 Vocational Diploma students. xxx xxx xxx xxx xxx xx xx xxx xx xx xxx xx

Direction:

1. Range = Max score - Min score = 180-152 = 28

2. Set Width or I =5 Number of Intervals = Range I

Draw a Frequency Distribution Table

Class Interval Mark Frequency (f)

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Example3: From Example2, Draw a 10 levels Frequency Distribution Table

Direction:

1. Range = Max score -Min score

2.Set the Class Interval to 10 levels

Draw a Frequency Distribution Table

Class Interval Mark Frequency(f)

Frequency Table has technical terms as follows:

1. Lower Limit ขีดจำกันล่าง is the minimum value of each Class Interval. For example, 21-30, 31-40, 41-50 The min value is 21,31,41

2.Upper Limit ขีดจำกัดบน is the maximum value of each Class Interval. For example, 21-30, 31-40, 41-50

The max value is 30,40,50

3.Lower Boundary ขอบล่าง is the mid-value between Lower Limit and next to Upper Limit of the below Class Interval.

Lower Boundary = the Lower Limit of Class Interval +the Upper Limit of the below Class Interval

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For example: the minimum value of Class Interval 21 -30 = 21+20/2 =20.5

4. Upper Boundary ขอบบน is the mid-value between Lower Limit and next to Upper Limit of the below Class Interval.

Lower Boundary = Upper Limit of the Class Interval + Lower Limit of the lower Class Interval

For example: Upper Boundary 0f Interval Class 21-30 = 30+31/2=30.5

5.Mid point จุดกึงกลาง is the middle of Class Interval range

Mid Point = Lower Boundary +Upper Boundary/2 or Mid Point = the Lower Limit of Class Interval +the Upper