If a data set has $\text{mean} = 32.5$ and $\text{standard deviation} = 7.1$, approximately how many standard deviations **below** the mean is a value of $20$?

Z-score: $z = \dfrac{x - \text{mean}}{\text{SD}} = \dfrac{20 - 32.5}{7.1} = \dfrac{-12.5}{7.1} \approx -1.76$. Rounded: about $-1.8$ SDs below the mean. - Trap D returns the *numerator* without dividing. - Trap A is the z-score for a value of $30$. - Trap B would require the value to be $32.5 - 7.1 = 25.4$, not $20$.