7-2 page 312
2 to 48, even numbered problems
Skip Chapter Section 7-3
7-4 page 339
2 to 28, even numbered problems
7-5 page 352
2 to 26, even numbered problems
7-5: Estimating the Standard Deviation of a population
The Greek letter σ (sigma) is the symbol that represents the standard deviation of a population.
To estimate σ, use the χ2 distribution, pictured above and tabulated in Table A-4, page 615 and the appropriate formulas.
The standard deviation measures how "spread out" the data is around the mean. The following examples illustrate when it might be useful to know a standard deviation.
How "spread out" are the body temperatures of healthy people?
How much do the volumes of gasoline dispensed by a pump at a gas station vary?
What is the typical variation of the waiting times for people standing in line at banks?
Technique to be learned: Based on the standard deviation, s of a sample of the population calculate an interval in which we are confident that the standard deviation, σ of the population exists.