document.write( "Question 1137970: In how many ways can a selection of at least two CDs be made from a set of 7 CDs \n" ); document.write( "
Algebra.Com's Answer #755869 by Edwin McCravy(20060)\"\" \"About 
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document.write( "For each of the 7 CD's, you have exactly 2 decisions to make:\r\n" );
document.write( "(1) Choose it!\r\n" );
document.write( "or\r\n" );
document.write( "(2) Don't choose it!\r\n" );
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document.write( "So there are 2×2×2×2×2×2×2 = 27 = 128 ways to make a decision for\r\n" );
document.write( "each CD, to choose or not choose it.  However, from that 128 we need to\r\n" );
document.write( "subtract:\r\n" );
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document.write( "(a) The 7 ways we could choose only 1 CD.\r\n" );
document.write( "and\r\n" );
document.write( "(b) The 1 way we could have chosen no CDs at all, which case is included in\r\n" );
document.write( "    the 128 as the one case where \"(2) Don't choose it!\" was decided for\r\n" );
document.write( "    every CD.\r\n" );
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document.write( "So the final answer is 128-7-1 = 120 ways.\r\n" );
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document.write( "Edwin
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