document.write( "Question 475749: In how many ways can 12 books be divided between A and B so that one may get 9 books and the other student 3 books? \r
\n" ); document.write( "\n" ); document.write( "Here is how I did it:
\n" ); document.write( "12C3 + 3C3 = 220+1 = 221 ways\r
\n" ); document.write( "\n" ); document.write( "OR\r
\n" ); document.write( "\n" ); document.write( "12C3 +9C9 = 220 + 1 = 221 ways. \r
\n" ); document.write( "\n" ); document.write( "The book's answer is 2*12C9 = 2*12C3 = 440 ways. But why my answer is not correct? Isn' t it true that once student A takes 9 books there are only three books left for the second student. So, that's why my calculation makes sense. \r
\n" ); document.write( "\n" ); document.write( "Could you help me explain why the textbook is right? Thank you very much. \r
\n" ); document.write( "\n" ); document.write( "I. \n" ); document.write( "

Algebra.Com's Answer #326237 by sudhanshu_kmr(1152) $\"\"$ $\"About$

You can put this solution on YOUR website!
12 books be divided between A and B so that one may get 9 books and the other student 3 books.\r
\n" ); document.write( "\n" ); document.write( "case 1: when A will get 9 books and B will get 3 books\r
\n" ); document.write( "\n" ); document.write( "number of ways = 12C9 * 3C3 = 220\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "case 2: when A will get 3 books and B will get 9 books\r
\n" ); document.write( "\n" ); document.write( "number of ways = 12C3 * 9C9 = 220\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "total number of ways = 220 + 220 = 440\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "if any doubt, you are welcome to contact..\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

\n" );