# Mean, Median, Mode, and Midrange of Grouped Data - PowerPoint PPT Presentation

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Mean, Median, Mode, and Midrange of Grouped Data. Section 2.5. Grouped Data……. You must add one more column than you did using ungrouped data. You now need a midpoint column. The symbol for the midpoint is. Formulas……Mean. Mean. Median.

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Mean, Median, Mode, and Midrange of Grouped Data

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## Mean, Median, Mode, and Midrange of Grouped Data

Section 2.5

### Grouped Data……

• You must add one more column than you did using ungrouped data.

• You now need a midpoint column.

• The symbol for the midpoint is .

• Mean

### Median

• There IS a formula to find the median using grouped data.

### Mode……

• Find the greatest frequency and read across the chart until you see the class that corresponds to it.

• Your answer will be the entire interval.

### Midrange…..

• Add the lowest number in the first row to the highest number in the last row.

• Divide that answer by 2.

### Example…..

• Find the mean, median, and mode of the set of grouped data.

### Median…..

• n/2 = 20/2 = 10

### Mode and Midrange……

• The mode is 21-26.

• Midrange =

### Now you try……….

• Find the mean, median, and mode of the following set.

### Mode……..

• The mode is 69-72.

### Midrange……..

• The midrange =

(63 + 78)/2 = 70.5

## Range, Variance and St. Deviation – Grouped

Section 2.5

### Grouped Data……

• Variance Formula

• Standard Deviation

### Range…..

• High number in last row minus low number in first row.

### Example……

• Find the variance, standard deviation, and range of the set.

### Calculator Steps……

• Put lower boundaries in L1 and upper boundaries in L2. Put frequencies in L3. Set a formula for midpoint in L4.

• Find f times midpoint by setting a formula in L5.

• Find f times midpoint squared in L6 by setting a formula.

### Your lists should look like this……

• Find the variance.

• Find the standard deviation.

### Range = High - Low

• Range = 32 – 2 = 30

### Example……

• Find the mean, median, mode, midrange, range, variance, and st. deviation of the data set.

### Mode……

• Greatest Frequency is 9.

• Mode = 15-20

### Homework…….

• Find the measures of center and variation for the grouped data on HW3.