document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1088494>Question 1088494</A>: <I><SPAN STYLE=\"word-break: break-all;\"> There are 5 red, 5 blue, 5 green and 5 yellow letters, each of which is inside one of twenty identical unmarked envelopes. What is the least number of envelopes selected in order to have at least 3 letters of the same color?<BR>\n" );
document.write( "a.4 b.8 c.9 d.12 </SPAN>\n" );
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document.write( "<U>Answer</U>. c) 9.\r<BR>\n" );
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document.write( "<U>Solution</U>\r<BR>\n" );
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document.write( "In worst case you will select 2 red, 2 blue, 2 green and 2 yellow letters after 8 trials.\r<BR>\n" );
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document.write( "Then on the 9-th trial you INEVITABLY will get 3 letters of the same color, independently which exactly color you will select at this trial.\r<BR>\n" );
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document.write( " </SPAN>\n" );
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