1. In your own words, define and discuss the importance of measures of dispersion or variability in statistical analyses. How do they differ from measures of central tendency?

2. A researcher wants to know about the primary type of drug used by students on a college campus. Her data is in the table below.Primary Drug Used by Students Drug f Marijuana 1250Cocaine/crack175 Heroin250 Hallucinogens 70 Other 385 a) Calculate the variation ratio for the data above. b) Describe and interpret your findings.

3. Ten rookie police officers started working at the Pine Valley Police Dept in 2005. At that time, they all began with the same salary ($36,000/year). Today, 10 years later, the salaries of those same 10 officers are the following: Police Officer Salaries 10 Years Posthire Officer Salary ($)148,000248,000350,000451,000552,000654,000757,000858,000962,0001069,000

a. Calculate the range, variance, and standard deviation of the data above. Describe the results. b. How would you explain the variation (or difference) in salaries?