Yellow (Maize) Car? ~
A loyal Michigan fan currently has a blue car. He plans to purchase a brand-new car and
is considering a yellow car. He wonders if purchasing a brand-new yellow car will hurt his ability to sell the car
in the future, say in three years. He decides to do some research about the average number of days it takes to
sell a three-year-old yellow car. The stated average number of days it takes to sell a three-year-old car of any
color is 30 days. He obtains a random sample of 40 yellow three-year-old cars up for sale and records the
number of days it takes to sell each car. He would like to use these results to assess if yellow cars take longer
to sell on average compared to that for three-year-old cars of any color, at the 5% level of significance.
This loyal Michigan fan expressed the hypotheses for the test as shown:
Briefly explain why these are not the correct hypotheses to be tested?
Suppose the average number of days it takes to sell a three-year-old yellow car really is 30 days. If we
were to repeat this study 60 times, each time taking a random sample of 40 yellow three-year-old cars up
for sale and conducting the same appropriate hypothesis test at the same significance level, then
decisions would we expect to be incorrect?
Stats 250 Fall 2017 Exam 2
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