SOLUTION: The scores on a particular test are normally distributed with mean of 73 and standard deviation 5. What score would a student need to be among the top 10% of all test scores?

Question 1012954: The scores on a particular test are normally distributed with mean of 73 and standard deviation 5. What score would a student need to be among the top 10% of all test scores?
After using the formula for determining the value of P16 (the 16th percentile) in a data set, the result is L = 5 (this whole number was obtained without rounding). How do we use this result to determine the value of P16?
Thank you.
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
z=(x-mu)/sd
z(0.90)=+1.28; because the top 10% occurs at the 90th percentile for z.
1.28=(x-73)/5
5*(1.28)=x-mu
6.4=x-mu
x=79.4
The 16th percentile occurs when z=-0.994
-0.994=(x-mu)/5
-5=x-mu
mu-5=x
x=68

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