White remains the most popular car color in the United States, but its
popularity appears to be slipping. According to an annual survey by DuPont
(Los Angeles Times, February 22,1994 ), white was the color of \(20 \%\) of the
vehicles purchased during 1993 , a decline of \(4 \%\) from the previous year.
(According to a DuPont spokesperson, white represents "innocence, purity,
honesty, and cleanliness.") A random sample of 400 cars purchased during this
period in a certain metropolitan area resulted in 100 cars that were white.
Does the proportion of all cars purchased in this area that are white appear
to differ from the national percentage? Test the relevant hypotheses using
\(\alpha=.05\). Does your conclusion change if \(\alpha=.01\) is used?