Question 1159661
If you mean ONE day and exactly ONE day.  (Meaning, not "one or more" days.):
<pr>
{{{(0.95)^364 * (0.05)^1 * (365!/(364!*1!))}}} 
<pr>
= 0.000000007787 * 0.05 * 365 
<pr>
= 0.0000001421

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<pr>
If you mean ONE OR MORE days:
<pr>
{{{1 - (0.95)^365}}}
<pr>
= 1 - 0.000000007398
<pr>
= 0.999999992602