Answer: The required answers are
(a) 0.25, (b) 0.62, (c) 6.
Step-by-step explanation: Given that we toss a fair coin 10 times and X denote the number of heads.
We are to find
(a) the probability that X=5
(b) the probability that X greater or equal than 5
(c) the minimum value of a such that P(X ≤ a) > 0.8.
We know that the probability of getting r heads out of n tosses in a toss of coin is given by the formula of binomial distribution as follows :

(a) The probability of getting 5 heads is given by

(b) The probability of getting 5 or more than 5 heads is

(c) Proceeding as in parts (a) and (b), we see that
if a = 10, then

Therefore, the minimum value of a is 6.
Hence, all the questions are answered.