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Hi,
I. Use Chebyshev’s theorem to find what percent of the values will fall between 248 and 320 for a data set with a mean of 284 
and standard deviation of 18.
 P(2 SD from mean) =  = .75  or 75%
 = .75  or 75%
II. Use the Empirical Rule to find what two values 95% of the data will fall between for a data set with a mean of 216 and standard deviation of 15.
 2 SD from mean:  216-30 = 186   and 216 + 30 = 246
     95% of the data will fall between 186 and 246