IQ test scores are normally distributed with a mean of 100 and a standard deviation of 15. An individualʹs IQ score is found to be 120. Find the z-score corresponding to this value.
A)1.33
B)-0.67
C)0.67
D)-1.33

Question

Quizplus · Accepted Answer

The z-score is calculated using the formula $z = \frac{(X - \mu)}{\sigma}$, where $X$ is the value in question, $\mu$ is the mean, and $\sigma$ is the standard deviation. Substituting the given values, $z = \frac{(120 - 100)}{15} = \frac{20}{15} = 1.33$.

IQ Test Scores Are Normally Distributed with a Mean of 100