We want to know if the average time to run a mile is different for athletes versus non- athletes. We will collect a random sample of students, ask them their typical time to run one mile, and whether or not they are an athlete. (We will only include students who actually run a mile or more.) Which confidence interval is best suited to this situation? One mean (sigma known) One mean (sigma unknown) O Mean of differences, using dependent samples (paired data). Difference of two means (independent samples) One proportion Difference of two proportions Slope of the regression line