An 8th grade history teached studied the statistics for her mid-term exam. The average grade for the mid-term was 84 points, and the standard deviation was 8 points. The Z-score for a student who scores 90 on the exam is:

Question

An 8th grade history teached studied the statistics for her mid-term exam.  The average grade for the mid-term was 84 points, and the standard deviation was 8 points.  The Z-score for a student who scores 90 on the exam is:
84-90/8= -0.75

Reiny · Answer

You have the subtraction backwards A score of 90 is above the mean, so the z-score should be positive z-score = (90-84)/8 = +.75