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# Birthday Problem

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i am trying to get the function: 1-365!/((365-n)!*365^n) to graph itself properly; this function/formula is more commonly known as, "the birthday problem." I am looking in to this merely for curiosity, but I am also interested because I'm trying to continue exercising my math skills now that I am no longer in college. Could someone please show me what is wrong with my formula or, if nothing is wrong with it mathematically, why I cannot get it to display on a graph as anything but a line? As an added note, I have substituted "n" as "x" when using the website's graphing feature.

Guest Nov 14, 2014

#2
+26642
+10

Here's a way of tackling the problem (approximately):

You could always improve on this by using the exact expression for small values of n, and switching to Stirlings approximation when you can no longer evaluate the exact expression.

.

Alan  Nov 14, 2014
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#1
+17721
+5

When I try graphing your function using my TI-83+, I keep getting an error ... I think because may calculator can't handle 365!

I believe that your formula is correct; it's just that the numbers are larger than your calculator's ability to handle them.

geno3141  Nov 14, 2014
#2
+26642
+10