Question 1191900
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mu = population mean of the class scores = 74
sigma = population standard deviation of the class scores = 7


z10=1.28 indicates the z score for the top 10 percent


This means P(Z > 1.28) = 0.10 approximately


Let's find the raw score x based on this z score
z = (x-mu)/sigma
x-mu = z*sigma
x = mu+z*sigma
x = 74+1.28*7
x = 82.96


The cut off between the highest B and the lowest A is an 82.96
If your teacher is rounding things to the nearest whole number, then it would be an 83.
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