Question

6. A fair coin is flipped repeatedly until 50 heads are observed. What is the probability that at least 80 flips are necessary? (You may calculate an approximate answer.)

Answer 1

So:- Given data, A fais coin is flipped repeatedly n=50 heads; the probability that atleast 80 flips are necessary | P ( x > Wo) coin is flipped: p(head) =0.5 & p (Tail)=0.5 Mean no. of flips required for 50 flips » nxt = 50 xos = Sox2 =100 Mean (M) = 100) (-p

Standard deviation 10) Tvar - Inx -P) = 50x2 - 1100 = 10 Standard deviation=10 P(X2 So) > p (x > 79.5) Flp (2c 79.50-100) (**24 394 = 1-P (24.-2005) =lp (22-205) table z 1-0.0202 (:Value taken from a Standard normal distribution = 0.9798 1: p(x280) = 0.9798