SOLUTION: Lewis earned 85 on his biology midterm and 81 on his history midterm. In the biology class the mean score was 79 with standard deviation 5. In the history class the mean score wa

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Question 129664: Lewis earned 85 on his biology midterm and 81 on his history midterm. In the biology class the mean score was 79 with standard deviation 5. In the history class the mean score was 76 with standard deviation 3.
a) Convert each midterm score to a standard z score.
b) On which test did he do better compared to the rest of the class
Answer by stanbon(75887) About Me  (Show Source):
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Lewis earned 85 on his biology midterm and 81 on his history midterm.
In the biology class the mean score was 79 with standard deviation 5.
In the history class the mean score was 76 with standard deviation 3.
a) Convert each midterm score to a standard z score.
Biology: z(85)=(85-79)/5 = 6/5 = 1.2
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History: z(81)=(81-76)/3 = 5/3 = 1.6666...
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b) On which test did he do better compared to the rest of the class
He did better in history because his score is 1.666 standard deviations
above the mean for the class.
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Cheers,
Stan H.