Let  us now take up some examples Example 31 If a fair coin  is tossed 10 times, find the probability of
(i)
exactly six heads
(ii)
at least six heads
(iii)
at most six heads
Solution The repeated tosses of a coin are Bernoulli trials Let X denote the number
of heads in an experiment of 10 trials Clearly, X has the binomial distribution with n = 10 and p = 1
2
Therefore
P(X = x) = nCxqn–xpx, x = 0, 1, 2,