An auto manufacturer leases cars to small businesses for use in visiting clients and other business travel. The contract

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An auto manufacturer leases cars to small businesses for use in
visiting clients and other business travel. The contracted lease
does not specify a mileage limit and instead includes a
depreciation fee of $0.30 per mile. The contract includes other
origination, maintenance, and damage fees in addition to the fee
that covers the mileage. These leases run for one year. A sample of
150 cars (all were a particular model of four-door sedan) returned
to their dealers early in this program averaged 21,714 miles, with
standard deviation s = 2,352miles. Currently, this manufacturer has
leased approximately 10,000 of these vehicles. When the program was
launched, the planning budget projected that the company would earn
(in depreciation fees) $6,500 on average per car.
Questions: 1. Is the sample size conditions for using a 95%
confidence interval for the mean number of miles driven per year
satisfied?
2. Does the method of sampling raise any concerns?
3. Construct the 95% confidence interval for the number of miles
driven per year on average for leased cars of this type. Interpret
the CI.
4. Construct the 95% confidence interval for the earnings over
the one-year lease, in a form suitable for presentation.
5. Interpret the CI in question 4. What is the implication for
the budget claim?