Question

The ages of employees at a certain company are normally distributed and the mean age is 36 with a standard deviation of 3 years. How many employees are between 30 and 42 years old?

Answer 1

The empirical rule for a normal distribution states that 95% of the data points lie within plus and minus two standard deviations from the mean. 30 is two standard deviations below the mean and 42 is two standard deviations above the mean.
Therefore, 95% if the employees are between 30 and 42 years old.