A normal distribution of data has a mean of 90 and a standard deviation of 18 What is the approximate z -score for the value 64 ?

Use the z-score formula: z = (value − mean) ÷ standard deviation. For 64, z = (64 − 90) ÷ 18 = −26 ÷ 18 ≈ −1.4. So the approximate z-score is negative 1 point 4, choice B.

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