Question

Find the z-score for the lower quartile of any normal curve.

A) 0.25
B) -0.67
C) 0
D) 1.25

Answer 1

The correct answer is B. The z-score for the lower quartile of a normal distribution is approximately -0.67, corresponding to the 25th percentile of the data.

Step-by-step explanation:

The z-score for the lower quartile of any normal curve, which is the first quartile (Q1) or the 25th percentile, is approximately -0.67. This is because the lower quartile divides the bottom 25% of data from the top 75%.

Since the normal distribution is symmetric, the value on the z-table that corresponds to an area of 0.25 (or 25% of the area under the curve to the left of the z-score) is a negative z-score.

Looking up the values in a standard normal distribution table or using standard statistical software, we can find the z-score that leaves 25% of the distribution to its left, which is approximately -0.67.