# Question: Determining percentage of probability

#### sditizio

##### New Member
Hello,

I'm in the middle of working on an assignment that involves determining probability. I wanted to see if I am on the right track. Any help would be greatly appreciated.

The question:
The heights of American women ages 10 to 24 are normally distributed with a mean of 65 inches and a standard dev of 2.4 inches. Women is chosen at random.

For the first part, I was asked to determine prob that woman is more than 67 inches tall. My answer is P=0.2033.

The second question is to determine prob that she is between 63 and 70 inches tall. I came up with p=0.779.

I need help answering the 3rd and 4th sections to this problem: How tall are the top 15% in this age bracket? And how tall are the bottom 20% of women in this age bracket?

#### BGM

##### TS Contributor
Haven't check your numerical solutions in the first two sections, but if you know how to find the answers in these sections, the problem in the latter sections is simply the inverse problem of them, i.e. you just need to "inversely" lookup your normal table / find the quantile function of your software.