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?
justaguide | Certified Educator
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
The required z-score is -2