Question

If you flip a fair coin five times what is the probability that you will get exactly 3 tales

Answer 1

Answer: 0.3125

As a fraction, 0.3125 = 5/16

================================================

Work Shown:

n = 5 trials

p = 0.5 is the probability of landing tails

x = 3 = number of tails we want to happen

Use the binomial PDF formula to get

(n C x)*(p)^x*(1-p)^(n-x)

(5 C 3)*(0.5)^3*(1-0.5)^(5-3)

10*(0.5)^3*(0.5)^(2)

0.3125

note: flipping a single coin 5 times is the same as flipping 5 independent coins one time