I agreed to help my cousin with her statistics, but to tell you the truth, I've never taken it. I went straight from Algebra 2 to Calc and then Calc 2 and so forth. Also, I haven't taken a math course in years. So a lot of this stuff I have either forgotten or never seen before. So please help!

The problem says:

A population has a mean of 78 and a standard deviation of 2.8. According to Chebyshev, at least what proportion of this population will lie between 97.6 and 58.4?

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Also, I had another question. This one said P(A and B-) is 0.6. B- stands for B with a line over it. What does B with a line over it stand for?

Full Problem says:

P(A) is 0.8 and P(A and B-) is 0.6. What is P(A and B)? (Hint-try a Venn diagram)