According to a newspaper, customers are not settling for automobiles straight off the production lines. A sample of 173 recent purchases of a particular car model yielded a sample mean of $4,878 above the $20,200 base sticker price. Suppose the cost of
accessories purchased for all cars of this model has a standard deviation of $1,568.
a. Calculate an 80% confidence interval for the average cost of accessories on this model.
b. Determine the margin of error in estimating the average cost of accessories on this model.
c. What sample size would be required to reduce the margin of error by 50%?