Answer:
68% of plans cost between $62.16 and $86.52.
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: 74.34
Standard deviation: 12.18
Bell-shaped is the same as normally distributed.
Estimate the number of plans that cost between $62.16 and $86.52.
62.16 is one standard deviation below the mean.
86.52 is one standard deviation above the mean.
By the Empirical rule, 68% of the measures are within 1 standard deviation of the mean.
So
68% of plans cost between $62.16 and $86.52.
