math prob! help!

<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>89.1%</p>

<p>Wikipedia's</a> explanation
Ask</a> Dr. Math explanation</p>

<p>(Just FYI to anyone else reading - this is definately not a SAT-level problem)</p>

<p>Unless you are in AP statistics, don't worry about this problem! :D</p>