Bjork larsen was trying to decide whether to use a new racing wax for cross-country skis. he decided that the wax would be worth the price if he could average less than 55 seconds on a course he knew well, so he planned to study the wax by racing on the course 8 times. his 8 race times were 56.3, 65.9, 50.5, 52.4, 46.5, 57.8, 52.2, and 43.2 seconds. should he buy the wax? explain by using a confidence interval.