<p>ok, someone please help me with this math problem. If there are 40 kids in my class, what is the probability that 2 have the same birthday? (please show me how you did this)</p>
<p>COMPLETELY in the wrong place, but here goes...</p>
<p>the probablility that the first person has a unique birthday is 365/365</p>
<p>the probability that the second person has a unique birthday is 364/365</p>
<p>etc...</p>
<p>so, therefore</p>
<p>there is a 365!/[(365^n)*(365-n)!] chance that they all have unique birthdays</p>
<p>I worked it out to about 11%. Therefore, there is an 89% chance that at least 2 have the same birthday.</p>