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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:
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:
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 $\mathrm{IQR}$ ? What does the $\mathrm{IQR}$ represent?
919
How many standard deviations away from the mean is the median?
0.03
Additional Information: The population FTES for 2005-2006 through 2010-2011 was given in an updated report. (Source: http://www.ltcc.edu/data/ResourcePDF/LTCC_FactBook_2010-11.pdf). The data are reported here.
Year | 2005-06 | 2006-07 | 2007-08 | 2008-09 | 2009-10 | 2010-11 |
Total FTES | 1585 | 1690 | 1735 | 1935 | 2021 | 1890 |
Calculate the mean, median, standard deviation, first quartile, the third quartile and the IQR. Round to one decimal place.
mean = 1809.3
median = 1812.5
standard deviation = 151.2
First quartile = 1690
Third quartile = 1935
IQR = 245
Construct a boxplot for the FTES for 2005-2006 through 2010-2011 and a boxplot for the FTES for 1976-1977 through 2004-2005.
Compare the IQR for the FTES for 1976-77 through 2004-2005 with the IQR for the FTES for 2005-2006 through 2010-2011. Why do you suppose the IQRs are so different?
Hint: Think about the number of years covered by each time period and what happened to higher education during those periods.
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