six black balls and six white balls of the same size are distributed among 10 urns so that atleat one ball is there in one urn

• a+b+c+d+e+f+g+h+i+j = 6+6=12
  since atleast one in each urn so,
  a'=a+1'b'=b+1,....and so on,
  a'+b'+....+j' = 12-10=2
  11C2.
• 8 years agoHelpfull: Yes(0) No(1)