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For getting an odd sum, we need a combination of Even+Odd or Odd+Even
So from 1–27; No. of odd numbered cards=14
No. of even numbered cards=13
Case1: Odd numbered card is drawn first
Probability = (14/27)*(13/26)= 7/27
Case2: Even numbered card is drawn first
Probability = (13/27)*(14/26)= 7/27
Hence probability of getting an odd sum = (7/27)+(7/27)= 14/27
