SOLUTION: Scores on a test are approximately normally distributed with a mean of 70 and a standard deviation of 9. The teacher wants to give A's to the top 10% of students and B's to the ne

Algebra ->  Probability-and-statistics -> SOLUTION: Scores on a test are approximately normally distributed with a mean of 70 and a standard deviation of 9. The teacher wants to give A's to the top 10% of students and B's to the ne      Log On


   

Question 581466: Scores on a test are approximately normally distributed with a mean of 70 and a standard deviation of 9. The teacher wants to give A's to the top 10% of students and B's to the next 23%. What is the bottom cut-off for a B grade? Round to the nearest whole number.
My answer = 76
Thank you very much!
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Scores on a test are approximately normally distributed with a mean of 70 and a standard deviation of 9. The teacher wants to give A's to the top 10% of students and B's to the next 23%. What is the bottom cut-off for a B grade? Round to the nearest whole number.
My answer = 76
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I get 71.5874
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invNorm(0.57) = 0.1764
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score = 0.1764*9+70 = 71.5874
Round up to 72
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Cheers,
Stan H.