Answer:
68% of an investment earning a return between 6 percent and 24 percent.
Step-by-step explanation:
The Empirical Rule states that, for a normally distributed random variable:
68% of the measures are within 1 standard deviation of the mean.
95% of the measures are within 2 standard deviation of the mean.
99.7% of the measures are within 3 standard deviations of the mean.
In this problem, we have that:
Mean = 15
Standard deviation = 9
How likely is it to earn a return between 6 percent and 24 percent?
6 = 15 - 1*9
6 is one standard deviation below the mean
24 = 15 + 1*9
24 is one standard deviation above the mean
By the empirical rule, there is a 68% of an investment earning a return between 6 percent and 24 percent.