Answer:
At least 95% of data falls between 4 and 20.
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 = 12
Standard deviation = 4
At least what percent of data falls between 4 and 20?
4 = 12 - 2*4
So 4 is two standard deviations below the mean
20 = 12 + 2*4
So 20 is two standard deviations above the mean
By the Empirical Rule, at least 95% of data falls between 4 and 20.
