document.write( "Question 1210234: Vera has 20 white socks, 21 black socks, 22 brown socks, 23 blue socks, 24 red socks, and 25 green socks. How many socks (at a minimum) must she pull out of her sock drawer to ensure at least six matching pairs of different colors?
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Algebra.Com's Answer #851711 by ikleyn(52781)![]() ![]() You can put this solution on YOUR website! . \n" ); document.write( "Vera has 20 white socks, 21 black socks, 22 brown socks, 23 blue socks, 24 red socks, and 25 green socks. \n" ); document.write( "How many socks (at a minimum) must she pull out of her sock drawer to ensure at least six matching pairs \n" ); document.write( "of different colors? \n" ); document.write( "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "In the worst case, Vera will take 25 green socks, 24 red socks, 23 blue socks, \n" ); document.write( "22 brown socks and 21 black socks - in all, 25 + 24 + 23 + 22 + 21 = 115 socks.\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " Notice that here I list the socks in the reverse order - \n" ); document.write( " according to their numbers of each color in the DESCENDING order.\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Then she will have a lot of matching pairs of 5 colors (green, red, blue, brown and black), \n" ); document.write( "but still will NOT have 6 matching pairs of different color.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "But after that, any two next socks will create the required 6-th pair of the white color.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So, the minimum number of socks Vera should draw from the drawer is 115 + 2 = 117, \n" ); document.write( "to have 6 guaranteed matching pairs of 6 different colors.\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "My answer coincides with the answer by @CPhill, but explanation/reasoning/logic \n" ); document.write( "is slightly different (more straightforward, in order for do not confuse a reader).\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Solved.\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |