Random samples of tires being replaced by a car dealer showed the tire life (miles) below, based

Question:

Random samples of tires being replaced by a car showed the tire life (miles) below, based on whether or not the owner had checked once a month for recommended tire Inflation. Use a = .05 In the following questions.
(a) Are the population variances equal?
(b) Do the population means differ?
(c) What is the advantage of answering (a) before (b)?
Dealer
A dealer in the securities market is an individual or firm who stands ready and willing to buy a security for its own account (at its bid price) or sell from its own account (at its ask price). A dealer seeks to profit from the spread between the...