The generating function approach does give the exact answer, but is not
easily implemented in Excel. You could do the generating fuctions manually,
or use a program that can do symbolic math, such as Maple, Mathematica, or
the open source package Maxima
http://maxima.sourceforge.net/index.shtml
Jerry
"mk9999999" wrote:
Hi jerry,
thanks for your help - i forgot to mention that the trials are independent
of each other.
your methods are all good but unfortunately i need an exact answer rather
than an estimation. if this is not possible in excel would it be possible to
do in any other porgrams?
cheers