Question: Retention rates. In 2004 the testing company ACT, Inc., reported on the percentage of first-year students at 4-year colleges who return for a second year. Their sample of 1139 students in private colleges showed a 74.9% retention rate, while the rate was 71.9% for the sample of 505 students at public colleges. Does this provide evidence that there's a difference in retention rates of firstyear students at public and private colleges?