A typing competency test yield scores with sample mean of 80.0 and standard deviation of 10.0 and histogram shows that distribution is roughly bell-shaped. Employ the empirical rule to answer.
a) What percentage of the scores must fall between 60 and 100?
b) What percentage of the scores must fall within 10 points of the mean?
c) About 99.7 of the scores must fall between what two values? The mean should be midway between those two values.