A fair coin is tossed infinite times then find the probability of 4th head occurs
exactly at 10th times.

• The total number of possibilities for the first ten flips is 2^10 = 1024. For the 4th head to occur on the 10th flip we need the first three heads to occur in the first 9 flips; this is given 9C3 = 84. There is only 1 way for the 4th head to occur on the 10th flip, therefore the probability is,
  
  84*1/1024 = 21/256.
  
• 10 years agoHelpfull: Yes(2) No(2)