Suppose your friend’s 8th grade sibling is 59.5 inches tall. Their class average height is 63.4 inches with a standard deviation of 2.1 inches.

Question

If you are 70 inches tall how do you compare to your friend’s sibling? Who is taller, relatively speaking?

Answer 1

Compute the individual z-scores. You’re z-score is (70-63.4)/2.1 = 3.14 while your sibling (59.5-63.4)/2.1 = -1.86. You are above the class average by 3.14 standard deviations and your sibling 1.86 standard deviations below the average.