SOLUTION: Igor’s statistics professor gives final grades that are normally distributed with a mean of 68 and a standard deviation of 10. The professor says that the top 5% of the class will

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Question 926324: Igor’s statistics professor gives final grades that are normally distributed with a mean of 68 and a standard deviation of 10. The professor says that the top 5% of the class will receive an A and the next 20% of the class will receive a B.
What is the minimum grade needed for an A?
What is the minimum grade needed for a B?

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
mean of 68 and a standard deviation of 10
....
the minimum grade needed for an A: 85
10(invNorm(.95)) + 68 = 10(invNorm(1.6449)) + 68 = 84.449
.........
What is the minimum grade needed for a B: 74
10(invNorm(.70)) + 68 = 10(invNorm(.5244)) + 68 = 73.244