Descriptive Statistics: Practice 2 1.9 2008/06/26 22:20:54 GMT-5 2008/10/27 13:26:22.766 GMT-5 Susan Dean deansusan@deanza.edu Barbara Illowsky illowskybarbara@deanza.edu Susan Dean deansusan@deanza.edu Barbara Illowsky illowskybarbara@deanza.edu Connexions cnx@cnx.org elementary statistics Practice exercise for Descriptive Statistics

Student Learning Objectives The student will calculate measures of the center of the data. The student will calculate the spread of the data.

Given The population parameters below describe the full-time equivalent number of students (FTES) each year at Lake Tahoe Community College from 1976-77 through 2004-2005. (Source: Graphically Speaking by Bill King, LTCC Institutional Research, December 2005). Use these values to answer the following questions: μ = 1000 FTES Median - 1014 FTES σ = 474 FTES First quartile = 528.5 FTES Third quartile = 1447.5 FTES n = 29 years

Calculate the Values A sample of 11 years is taken. About how many are expected to have a FTES of 1014 or above? Explain how you determined your answer. 6 75% of all years have a FTES: aAt or below: bAt or above: a1447.5 b528.5 The population standard deviation = 474 FTES What percent of the FTES were from 528.5 to 1447.5? How do you know? 50% What is the IQR? What does the IQR represent? 919 How many standard deviations away from the mean is the median? 0.03