The denominator (bottom) of the z-score formula is

The denominator (bottom) of the z-score formula is (a) The standard deviation

(b) The difference between a score and the mean

(c) The range

(d) The mean

✅ Correct option: (a) The standard deviation

Explanation:

A z-score represents how far a particular score is from the mean in terms of standard deviation units. The formula for a z-score is: z = (X − Mean) / Standard Deviation Here, the denominator is the standard deviation, which standardizes the difference between the score and the mean. This allows comparison of scores from different distributions. Without dividing by the standard deviation, the score difference would not reflect variability in the data. Hence, the standard deviation is a critical component of the z-score formula.

10 Related PPSC Facts:

Z-score shows relative position. Mean is subtracted in numerator. Standard deviation standardizes score. Z-score can be positive or negative. Z-score of 0 equals the mean. Used in normal distribution. Z-scores allow comparison across tests. Larger SD lowers z-score magnitude. Used in hypothesis testing. Z-tables convert z-scores to probabilities.