Here is the question.  How to find the 90th percentile value for a
table of normally distributed data?

Mean	216.8789144
Median	196
Standard Deviation	120.8120967
Sample Variance	14595.56271
Minimum	0
Maximum	1103
Sum	103885
Count	479
Largest(1)	1103
Smallest(1)	0


I have a formula that will i believe will work but I am missing the
Z-value.  Here is the formula:

X = 90th percentile value

X = mean + (Zscore)(StandardDeviation)

My research tells me that I need to reference known tables (p table?
or t table?) to find out the z score for a given percentile based on a
normal distribution.  I am not able to find these tables to complete
the equation.

Thanks,

Those numbers are not consistent with normally distributed data.  The
normal curve is symmetrical, but your max value differs from the
median by almost 5 times as much as your min value does.  If you
provide some information on what kind of data it is, it may be easier
to help.

Just plug in your values here, and you won't even need a table-- it
will give you an exact value.
http://www.graphpad.com/quickcalcs/PValue1.cfm