Respuesta :
Let X be the number of tail when a coin is flipped n number of times. Let n is the number of times a coin is flipped. Let p be the probability of getting tail on any flip of coin.
Here as coin is fair coin the chance of getting head or tail at any flip is 1/2.
n=75, p =0.5
From given information X follows Binomial distribution with n=75 and p=0.5
The probability that getting tail 35 or fewer times is
P(X ≤ 35) = P(X=35) + P(X=34) + P(X=33) + ....+ P(X=2) + P(x=1)
The Binomial probability is calculated using probability function
[tex] P(X=k) = (nCk) p^{k} (1-p) ^{n-k} [/tex]
For given parameters n=75 and p=0.5 the probability of getting X=k is
[tex] P(X=k) = (75Ck) 0.5^{k} (1-0.5) ^{75-k} [/tex]
Using excel function to find cumulative binomial probability for x=1 to 35 is
=BINOM.DIST(35,75,0.5,1) = 0.322
The probability there will be 35 or fewer tails is 0.322
The percentage of getting 35 or fewer tails is 32.2%
