SOLUTION: Let us assume that the grades of 500 students are normally distributed with 𝜇=45 and standard deviation 𝜎=20. If the 20% of the students get excellent, what is the grade that

Algebra ->  Probability-and-statistics -> SOLUTION: Let us assume that the grades of 500 students are normally distributed with 𝜇=45 and standard deviation 𝜎=20. If the 20% of the students get excellent, what is the grade that      Log On


   

Question 1185778: Let us assume that the grades of 500 students are normally distributed with 𝜇=45 and standard deviation 𝜎=20. If the 20% of the students get excellent, what is the grade that determines the excellent? (What is 𝛸 value?)
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
z for the top 20% is +0.8416
z=(x-mean)/sd
0.8416=(x-45)/20
16.8=x-45
x=61.8 the grade