Question

A box contains three coins which have the same look. However, two of them are fair and theother one is biased withP(H) = 0.3. A coin is randomly selected from the box and tossed 10 times.(a)[15 points] What is the probability of observing exactly 3 heads?

Answer 1

0.1673 (16.73%)

Explanation:

The probability that a fair coin is chosen is 2/3 . if the fair coin is chosen the probability of getting 3 heads is determined by binomial distribution:

P(3 heads in 10 flips )=B(n=10,p=0.5,X=3) =0.1171

But if a coin that is not fair is chosen , then the probability of getting 3 heads also follows a binomial distribution but with p=0.3

P(3 heads)=B(n=10,p=0.3,X=3)=0.2668

Finally the probability is

P= 2/3*0.1171 + 1/3* 0.2678 = 0.1673 (16.73%)