Microlenders are institutions that lend relatively small amounts of money to businesses. An article on microlenders compared the average return on equity for lenders of two categories based on their credit ratings: Alpha versus Beta. For the Alpha group, a random sample of 74 firms, the average return on equity was 28%. For the Beta group, a random sample of 65 firms, the average return on equity was 22%.Assume both sample standard deviations were 6%, and test for equality of mean return on investment using α = 0.05.