Question

Assume that a randomly selected subject is given the same bone density test. Bone density test scores are normally distributed with a mean of 0 and a standard deviation of 1. Draw a graph and find p38 the 38th percentile this is what bone density score separating the bottom 38% from the top 62 %

Answer 1

Solution:

Given:  Bone density test scores are normally distributed with a mean of 0 and a standard deviation of 1.

We have to find  the 38th percentile this is what bone density score separating the bottom 38% from the top 62 %

Since mean is 0 and standard deviation is, we can use Standard normal distribution to find x value.

Look in z table for area = 0.3800 or its closest area and find corresponding z value.

Area 0.3783 is closest to 0.3800 and it corresponds to -0.3 and 0.01

thus z = -0.31

that is: x = -0.31

Thus the 38th percentile bone density = -0.31