document.write( "Question 673995: A disc jockey has 9 songs to play. Five are slow songs, and 4 are fast songs. Each song is to be played only once. In how many ways can the disc jockey play the 9 songs if
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document.write( "The songs can be played in any order.
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document.write( "The first song must be a slow song and the last song must be a slow song.
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document.write( "The first two songs must be fast songs.\r
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document.write( "Can you please explain this as you go. I not just out for an easy answer, I need insturction.PLEASE \n" );
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Algebra.Com's Answer #418977 by chandrumail(4)![]() ![]() ![]() You can put this solution on YOUR website! 1) The songs can be played in any order:\r \n" ); document.write( "\n" ); document.write( " No of ways the 9 songs can be played = 9! = 362880\r \n" ); document.write( "\n" ); document.write( "Explanation: the 1st song can be chosen from any of the 9 songs, the 2nd played song can be chosen from the remanining 8 songs, the 3rd played song can be chosen from the remaining 6 songs, the 5th played song can be chosen from the remaining 5 songs, the 6th played song can be chosen from the remaining 4 songs, the 7th played song can be chosen from the remaining 3 songs, the 8th played song can be chosen from the remaining 2 songs and the 9th played song can be chosen from the remaining 1 song. Hence the no of ways = 9*8*7*....2*1 =9!\r \n" ); document.write( "\n" ); document.write( "2) The first song must be a slow song and the last song must be a slow song.\r \n" ); document.write( "\n" ); document.write( "No of ways the 1st song can be chosen = 5 (as there are 5 slow songs) \n" ); document.write( "No of ways the 9th song can be chosen = 4 (as there are 4 remaining slow songs left) \r \n" ); document.write( "\n" ); document.write( "Having chosen the 1st and 9th, the songs 2 thru 8 can be chosen in 7! ways\r \n" ); document.write( "\n" ); document.write( "Total no of ways = 7!*5*4 = 100800 ways\r \n" ); document.write( "\n" ); document.write( "3) The first two songs must be fast songs.\r \n" ); document.write( "\n" ); document.write( "No of ways to select 1st song = 4 (as there are 4 fast songs) \n" ); document.write( "No of ways to select 2nd song = 3 (as there are remaining 3 fast songs)\r \n" ); document.write( "\n" ); document.write( "Having chosen 1st and 2nd song, the songs 3 thru 9 can be chosen in 7! ways\r \n" ); document.write( "\n" ); document.write( "Total no of ways = 7!*4*3 = 60480\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |