The mean score of a placement exam for entrance into a math class is​ 80, with a standard deviation of 10. Use the empirical rule to find the percentage of scores that lie between 60 and 80.​ (Assume...

The mean score of a placement exam for entrance into a math class is​ 80, with a standard deviation of 10. Use the empirical rule to find the percentage of scores that lie between 60 and 80.​ (Assume the data set has a​ bell-shaped distribution.)