$2.$ To raise awareness of its capabilities, FedEx developed a sales promotion that was sent to selected offices. To assess the possible benefit of the promotion, FedEx pulled the shipping records for a random sample of $50$ offices that received the promotion and another random sample of $75$ that did not and collected data on the number of mailings. They want to see if those who received the sales promotions shipped more mailings. The complete set of results is provided in the Module $7$ assignment data file $($promotions columns$).$