Question 286222
After the first exam the professor reports to the class that the mean for the exam was 73, and the standard deviation was 7. 
If the bottom 10% of the class fail the exam, what score would earn a student a failing grade?
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Find the z-value with a 10% left tail:
invNorm(0.10) = -1.2816...
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Find the score corresponding to that z-score:
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x = zs+u
x = -1.2816*7 + 73
x = 64.029
Scores below that fail.
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Cheers,
Stan H.