For each element in a set of size 2n,an unbiased coin is tossed. The 2ncoin tosses are
independent. An element is chosen if the corresponding coin toss were head. The probability
that exactly n elements are chosen is:

• total size of set=2n
  total solution space for con=2
  so probability of Head=1/2=probability of Tail
  the prob that exactly n elements are chosen=2nCn (1/2)^n (1/2)2n-n
  =2nCn (1/2)^2n
  2nCn/4^n
• 9 years agoHelpfull: Yes(0) No(0)