A sociologist studying the justice system has just written a paper detailing her findings after she examined the records of thousands of inmates. Among other things, she looked at the prison terms actually served by inmates who had been sentenced to five to ten years for a felony conviction. She found that the mean term actually served by those inmates was 42 months, with a standard deviation of 12 months. Suppose that these measures are valid for the population of all inmates who have been sentenced to five to ten years for a felony conviction. Complete the following statements about the distribution of all prison terms actually served by inmates sentenced to five to ten years for a felony conviction

Okay now here are my questions about the above
A) according to chebyshev's theorem at least ? % of the prison terms actually served lies between 12 months and 72 months? (you can choose 56, 75, 84, and 89 %)
B) According to chebyshev's theorem at least ? % of the prison terms actually served lies between 18 and 66 months? ( you can choose 56, 75,84, and 89 %)
C) Suppose that the distribution is bell shaped according to the empirical rule approximately ? of the prison terms actually served lies between 18 and 66 months? ( you can choose between 68, 75, 95, 95.7 %)
D) Suppose that the distribution is bell shaped according to the empirical rule approximately 68% of the prison terms actually lies between ? and ? months? ( I think that this one may be 12 and 72 months, but that is a guess)
Any help would be greatly appreciated!~

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