Mat 135: HW 3

What is standard deviation?

standard deviation is the square root of the variance, which attempts to summarize the variability or dispersion of values relative to the mean of the entire set. - http://www.free-online-calculator-use.com/standard-deviation-calculator.html#sthash.eCKVJnpN.dpuf

How do you find the coefficient of variation?

Mean/Standard Deviation *100, expressed in percents

What is the formula for finding the range?

Range = Highest Value - Lowest Value

How do I find the variance of a sample?

Step 1: Add up the numbers in your given data set. Step 2: Square your answer, and divide by the number of items - Set this number aside for a moment. Step 3: Take your set of original numbers from Step 1, and square them individually - Add those numbers (the squares) together: Step 4: Subtract the amount in Step 2 from the amount in Step 3. -Set this number aside for a moment. Step 5: Subtract 1 from the number of items in your data set. For example: 6 - 1 = 5 Step 6: Divide the number in Step 4 by the number in Step 5. This gives you the variance:

What is range?

The range is the difference between the largest and smallest values in a set of values. For example, consider the following numbers: 1, 3, 4, 5, 5, 6, 7, 11. For this set of numbers, the range would be 11 - 1 or 10.

How do you find the midpoint of a class?

The upper limit + the lower limit and divide by 2

What does a variance of zero mean?

There is no variability; all the numbers in the data set are the same. The data set 12, 12, 12, 12, 12 has a variance of zero (the numbers are identical).

What is variance?

Variance measures how far a data set is spread out. The technical definition is "The average of the squared differences from the mean," but all it really does is to give you a very general idea of the spread of your data. The data set 12, 12, 12, 12, 13 has a variance of 0.167; a small change in the numbers equals a very small variance The data set 12, 12, 12, 12, 13,013 has a variance of 28171000; a large change in the numbers equals a very large variance.

The symbol for population mean

mu

The symbol for sample mean

x bar

What is the formula for finding the mean?

xbar or mu =(the sum of all values)/(number of values)

What is the formula for finding the SAMPLE Mean?

xbar=(the sum of all values)/(number of values) xbar=sample mean Ex= the sum of all values n=the number of values

What is the mean?

It is the average; add up all your data, then divide by the number of data points

The symbol for standard deviation of a POPULATION?

sigma

The symbol for population variance

sigma squared

What is the formula for finding the POPULATION mean?

mu =(the sum of all values)/(number of values)

The symbol for sample standard deviation of a SAMPLE

s

The symbol for sample variance

s two