White remains the most popular car color in the US, but its popularity appears to be slipping relative to other colors. According to an annual survey by DuPont (LA Times, 2/22/1994), white was
the color of 20% of the vehicles purchased during 1993, a decline of 4% from the previous year. A
random sample of 400 cars purchased during this period in a certain metropolitan area resulted in
100 that were white. Does the proportion of all cars purchased in this area that were white appear
to differ from the national percentage? Test the relevant hypotheses using a = .05. Does your
conclusion change if a = 01 is used?