Question

what is the probability that one will obtain 7 heads if an unbiased coin is tossed 25 times? 10 times? at least 10 heads? at most 5 heads?

Answer 1

In 10 tosses, heads can occur in any of the 6 tosses and tails in the remaining 4 tosses. Coin being unbiased, probability of exactly 6 heads is 10C6(.5)^6*(.5)^4 = 210/1024.