document.write( "Question 1051953: This is known as the Birthday Problem.
\n" ); document.write( "(a) Consider a class with 30 students. Compute the probability that at least two of them
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\n" ); document.write( "(b) How many students should be in class in order to have this probability above 0.5? \n" ); document.write( "
Algebra.Com's Answer #667395 by Edwin McCravy(20060)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "The complement event would be for all 30 students to have\r\n" );
document.write( "all different birthdays.  There are 365P30 ways to assign\r\n" );
document.write( "them all different birthdays and 36530 ways to assign\r\n" );
document.write( "then any birthdays.  So the probability of all 30 having\r\n" );
document.write( "different birthdays is\r\n" );
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document.write( "\"%22%22=%22%22\"\r\n" );
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document.write( "\"%22%22=%22%22\"\r\n" );
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document.write( "So the probability that at least 2 students have the same birthday is\r\n" );
document.write( "that number subtracted from 1, which is:\r\n" );
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document.write( "or about a 71% probability that at least 2 students among the 30\r\n" );
document.write( "have the same birthday.\r\n" );
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document.write( "Edwin
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