Question

If a fair coin is tossed 4 times, what is the probability, to the nearest thousandth, of getting exactly 3 tails?

Answer 1

prob(heads) = 1/2

prob(not heads) = 1/2
prob(exactly 3 tails out of 4 tries)
= C(4,3)(1/2)^3 (1/2)^1
= 4(1/2)^4
= 4/16 = 1/4 = .250