Question

A fair coin is tossed infinite number of times. the probability that a head turns up for the first time after even number of tosses is

Answer 1

probability of getting head = 1/2
probability of getting tail =1/2 =probability of getting not a head
acc to ques required probability =p(t) p(t) p(h) +p (t) p(t) p(t) p(t) p(h)+...............
=1/2 1/2 1/2 +1/2 1/2 1/2 1/2 1/2+.............
=1/2^3+ 1/2^5+ 1/2^7+..........