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SMO 2009 Senior Round 1 Question 8

SMO · SMO 2009 Senior Round 1

Question 8

There are eight envelopes numbered $1$ to $8$. Find the number of ways in which $4$ identical red buttons and $4$ identical blue buttons can be put in the envelopes such that each envelope contains exactly one button, and the sum of the numbers on the envelopes containing the red buttons is more than the sum of the numbers on the envelopes containing the blue buttons.
  1. $35$
  2. $34$
  3. $32$
  4. $31$
  5. $62$