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The remaining questions refer to the following information:
Suppose the scores on an exam are normally distributed with a mean μ = 75 points, and standard deviation σ = 8 points.
ANSWER:
Suppose that the top 4% of the exams will be given an A+. In order to be given an A+, an exam must earn at least what score?
Good job! We need to find the exam score such that the probability of getting a score above it is 0.04. Equivalently (and more practical, given the way our table works) we need to find the exam score such that the probability of getting a score below it is 1 – 0.04 = 0.96. Looking in the body of the table for the table entry that is closest to 0.96 (which is 0.9599) we learn that the exam score that we are looking for has a z-score of 1.75. This means that the exam score that we are looking for is 1.75 * SD above the mean, and therefore is: 75 + 1.75 * SD = 75 + 14 = 89.