document.write( "Question 758671: there are 5 boys and 3 girls .in how many ways can they stand in a row so that no girls are together
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Algebra.Com's Answer #852528 by math_tutor2020(3828) ![]() You can put this solution on YOUR website! \n" ); document.write( "Answer: 14400\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Explanation \n" ); document.write( "There are 5 boys and 5! = 5*4*3*2*1 = 120 ways to arrange the boys.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Let's give the boys names such as: \n" ); document.write( "Alex \n" ); document.write( "Bill \n" ); document.write( "Carl \n" ); document.write( "Dave \n" ); document.write( "Eddy \n" ); document.write( "Or simply A,B,C,D,E for short.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Place blank markers between each pair of adjacent letters. \n" ); document.write( "Also, place blanks at the start and end of the sequence.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "We'll have this \n" ); document.write( "_, A, _, B, _, C, _, D, _, E, _\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Each blank space represents a possible spot for a girl to be placed. \n" ); document.write( "This is to guarantee the girls are not together (i.e there aren't any girls paired up nor are the 3 girls in one block).\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "There are 5 boys and 5+1 = 6 blank slots. \n" ); document.write( "Use the nCr combination formula to determine there are 6C3 = 20 ways to select the 3 blank slots.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Once a blank slot trio is selected, there would be 3! = 3*2*1 = 6 ways to arrange the girls in those slots.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "To recap quickly: \n" ); document.write( "120 ways to arrange the boys \n" ); document.write( "20 ways to pick the 3 blank slots \n" ); document.write( "6 ways to arrange the girls for any given slot trio selection\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Therefore we have 120*20*6 = 14400 different arrangements where the girls are not together, i.e. no girls are next to each other. \n" ); document.write( " \n" ); document.write( " |