Question

A fair coin is tossed 100 times. The probability of getting tails on odd number of times is

Answer 1

It could be 50% to get tails an odd number of time

Answer 2

Answer:

Let X denote the number of tails. Then X is a binomial variate with parameters

n=100 P=1/2

∴P(x=r)=100Cr(1/2)^100

r=0,1,2,3,4............100

Required probability = P(x=1)+P(x=3)+p(X=5)...........+P(x=99)

=(1/2)^100×[100C1+100C3+.....+100C99]

=(1/2)^100*(2^99)

=1/2