SOLUTION: Your final statistics averages are typically approximately normally distributed with a mean of 80 and standard deviation of 8. Professor Han says that the top 15% of the class will

Question 821688: Your final statistics averages are typically approximately normally distributed with a mean of 80 and standard deviation of 8. Professor Han says that the top 15% of the class will receive an A; the next 29%, a B; the next 41%, a C; the next 10% a D; and the bottom 5% an F.
(a). What grade must you exceed to obtain an A?
(b). What grade must you obtain to pass the course (C or better)?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Your final statistics averages are typically approximately normally distributed with a mean of 80 and standard deviation of 8. Professor Han says that the top 15% of the class will receive an A; the next 29%, a B; the next 41%, a C; the next 10% a D; and the bottom 5% an F.
(a). What grade must you exceed to obtain an A?
Find the z-value with a left tail of 0.85.
invNorm(0.85) = 1.0464
Find the corresponding percent::
x = z*s + u
x = 1.0364*8+80 = 88.29
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(b). What grade must you obtain to pass the course (C or better)?
Find the z-value with a left tail of 0.15
invNorm(0.15) = -1.0464
x = -1.0464*8+80 = 71.71
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Cheers,
Stan H.
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