Toyota Motor Corporation developed the Scion car model to appeal to young consumers. Toyota claims the average age of a Scion driver is 26 years old. Suppose a random sample of 18 Scion drivers was drawn, and the average age of the drivers was found to be 27.5 years. Assume the standard deviation for the age of scion drivers is 2.3 years.
a. Construct a 95% confidence interval to estimate the average age of a Scion driver.
b. Does this result lend support to Toyota’s claim?
c. What assumption needs to be made for this procedure?
d. Verify your results with Excel.