Statistics and Probability Question

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I have been stuck on these two for two hours....

In a particular forest, it is known that the circumference of 10 year old oak trees when measured three feet above the ground is 20 inches with a standard deviation of 4.5 inches. It is also known that these circumferences follow a bell-shaped distribution. If a random sample of 200 ten year old oak trees is selected, approximately how many would have girths greater than 29 inches?

AND...

Given that P(A) = 0.44, P(B) = 0.64, and P(A OR B) = 0.4224. Are A and B independent or dependent events? Why? Are A and B disjoint events? Why?

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View best answer, chosen by TB54321

@TB54321,

What percentage of a normal population has a value greater than two standard deviations above the mean?
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P(A or B) = P(A) + P(B) - P(A and B). You know the first three terms, so you can solve for P(A and B).
A and B are independent iff P(A and B) = P(A) * P(B). Now you can answer the independence question.
A and B are disjoint iff P(A and B) = 0. And you can answer the disjoint question.

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