Using the data in Exercise 3.5, construct a frequency distribution.
a. Determine the approximate values of the mean and standard deviation.
b. Compare the approximate values from part (a) with the actual values.
c. Construct a frequency distribution with twice as many classes as before, then repeat parts (a) and (b). Have the approximations improved?
d. If you were to construct a “frequency distribution” in which each data value was at the midpoint of its own class, what values do you think the “approximations” would have? Explain.

Year Percentage Year Percentage 1988 9.03 1998 6.95 1989 9.10 1999 6.71 1990 8.89 2000 7.05 1991 8.63 2001 6.31 1992 8.08 2002 5.38 1993 7.52 2003 5.03 1994 7.14 2004 4.80 1995 7.41 2005 4.90 1996 7.25 2006 5.35 1997 7.35 2007 5.71