SOLUTION: The foreign service exam gives a passing grade to only the top 10% of those taking the exam. The mean score is 84, with a standard deviation of 8. What should be the minimum passin

Question 418692: The foreign service exam gives a passing grade to only the top 10% of those taking the exam. The mean score is 84, with a standard deviation of 8. What should be the minimum passing grade?
(I really need a work-out without calculator shortcuts...)
Answer by ewatrrr(24785) (Show Source): You can put this solution on YOUR website!



Hi

NORMSINV(0.9) = 1.28 (using Excel function)

Value may also easily be found in a Table for:

 "Percentiles of the Standard Normal Distribution"

 1.28 = X -84 /8

 8(1.28)+84 = X

 10.25 + 84 = 94.25 or 95 would be minumum passing grade



Note: Using X = 94  gives 10/8 = 1.25 which doesn't get You into the 90%

       

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