What is the conditional probability that exactly four heads appear when a coin is flipped five times.? It is given that the first flip came up heads?
This is the same as that exactly three heads come up in the 2nd through 5th
flip. The number of heads in these 4 flips ~B(4,0.5), so is:
p = prob(4 H from 5 flips|first is H) = b(3;4,0.5)
Now look the probability mass function for the binomial distribution up in your
notes and/ot text to evaluate p.
RonL