Unformatted text preview: 3. Let Z be the standard normal variable. In each of the following, ﬁnd a.
(a) P (Z ≤ a) = 0.7524 (b) P (Z ≥ a) = 0.4268 (c) P (Z ≥ −a) = 0.2657 (d) P (−a ≤ Z ≤ a) = 0.7587 4. Annual salaries at a local company are normally distributed with a mean of $30,000 and a standard deviation of $5,000. If a person is
randomly selected from the company, what is the probability that their annual salary is more than $25,000? 5. Grades on a history exam were normally distributed with a mean of 75 and a standard deviation of 10. If 8% of the students received an A,
15% received a B, and 38% received a C, what is the cut-oﬀ for an A, B, and C? ...
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