Question 4.18: What z-score corresponds to the 75th percentile of a normal ...

To answer this question, we use the z table in reverse. We need to find the z-score for
which 75% of the area of the curve is to the left. From the body of the table, the closest
I area to 75% is 0.7486, corTesponding to a z-score of 0.67. Therefore the 75th percentile
is approximately 0.67. By the symmetry of the curve, the 25th percentile is z = – 0.67
(this can also be looked up in the table directly). See Figure 4.7. The median is z = 0.