Scores on a test have a mean of 70 and a standard deviation of 11. Michelle has a score of 48. What is Michelle's z-score?

Expert Answers

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The z-score for a number x, in a population subset with an average x' and a standard deviation s is equal to

z-score = (x - x')/s

Substituting the values we have here, x = 48, x' = 70 and s = 11

z = (48 - 70)/11

=> -22/11

=> -2

The required z-score is -2

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