Do people who smoke have higher cholesterol levels than people who do not smoke? A random sample of 315 subjects includes 43 who identify themselves as smokers and 272 who claim to be nonsmokers. Each subject's cholesterol level is measured. The average cholesterol level of the 43 smokers is 269.7; the average cholesterol level of the 272 nonsmokers is 229.5 At a 5% significance level, does this data provide evidence that the mean cholesterol level of smokers is higher than that of nonsmokers?