Question 136143
We need to find the SD that yields 90% below it. There are tables of SD that give area between +-SD. Let's use that type of table.

In order to find the SD that gives 90% below, we need to allow for the fact that we are going to include the entire lower half of the normal curve. If we want the upper limit to include 90%, then we will have 40% above the mean. 

We need to find the SD value from our table that yields 2*40% = 80% between +-SD. In my table, that is a value of 1.2816.  

You can get this from your TI-83 like tis -->http://people.hsc.edu/faculty-staff/robbk/Math121/TI-83/InvStdNormal.html

So Jen is {{{63.5 + 2.4*1.2816}}}