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**shatrocious** Hi everyone.. I am doing an at-home university course on Statistics for Business and Economics, I have been out of school for a number of years now and I need a little help.

I have just finished reading and learning Chebyshev's Theorum, z-Scores, and Empirical Rule.. i understand them, and did the first 5 problems without a hitch.

Heres what ive run in to that i dont get:

Of 1154 adults, average hours of sleep per night is 6.9, standard deviation is 1.2

a) use chebyshevs to find percentage that sleep between 4.5 and 9.3 - i worked that one out to be 75%

b) use chebyshevs to find % thats between 3.3 and 9.9..... heres where i am stuck, 6.9 - 3.3 = 3.6, 6.9 - 9.9 = -3.0

3.6 and -3.0 are not.. that same number of standard deviations apart. None of the methods or notes in the chapter tell me how to use this. All of the previous problems had the same number of SD's apart.. such as -2.4 and 2.4 in the a) part of the question.