A credit score is used by credit agencies​ (such as mortgage companies and​ banks) to assess the creditworthiness of individuals. Values range from 300 to​ 850, with a credit score over 700 considered to be a quality credit risk. According to a​ survey, the mean credit score is . A credit analyst wondered whether​ high-income individuals​ (incomes in excess of​ $100,000 per​ year) had higher credit scores. He obtained a random sample of ​high-income individuals and found the sample mean credit score to be with a standard deviation of . Conduct the appropriate test to determine if​ high-income individuals have higher credit scores at the level of significance.