In: Statistics and Probability
A biased coin is flipped 20 times in a row. The coin has a probability 0.75 of showing Heads.
a. What’s the probability that you get exactly 8 Heads?
b. What’s the probability that you get exactly 8 Heads, given that the first 2 flips show Heads?
c. What’s the probability that you never see the same result consecutively( never see 2H or 2T in a row)
a) The probability that there are exactly 8 heads is computed using the binomial probabiltiy function as:
Therefore 0.000752 is the required probability here.
b) Probability that we get exactly 8 Heads, given that the first 2 flips show Heads
= Probability that there are exactly 6 heads in the next 18 tosses, as there were already 2 heads in the first 2 tosses
Therefore 0.000197 is the required probability here.
c) The probability that you never see the same result consecutively is computed here as:
= P(HTHTHTH....) + P(THTHTHTH....)
= 2*0.520 = 0.519
Therefore 0.519 is the required probability here.