thinking mathematically statistics: 12.3 measures of dispersion
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Thinking Mathematically
Statistics:12.3 Measures of Dispersion
The RangeThe range, the difference between the highest
and lowest data values in a data set, indicates the total spread of the data.
Range = highest data value - lowest data valueExercise Set 12.3 #5
Find the range for 3, 3, 4, 4, 5, 5
Computing the Standard Deviation for a Data Set
1. Find the mean of the data items.
2. Find the deviation of each data item from the mean: data item - mean
3. Square each deviation: (data item - mean)2
4. Sum the squared deviations: add up all of the (data item - mean)2
Computing the Standard Deviation for a Data Set cont.
5. Divide the sum in step 4 by n-1, where n represents the number of data item.
6. Take the square root of the quotient in step 5. This value is the standard deviation for the data set. Standard deviation =
(data item mean)2
n 1
Example Standard Deviation
Exercise Set 12.3 #17Find the standard deviation for 1, 2, 3, 4, 5
Thinking Mathematically
Statistics:12.3 Measures of Dispersion
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