basic probability question

Question

I met the question in my exam:

flip one coin, the probability of head is 1/3, Pr{tail} = 2/3. Flip the coin twice, what are the four possible outcomes and their probabilities?

user6023 · Answer 1 · 2011-03-17 05:02:33Z

up vote 3 down vote

Head Head 1/3 * 1/3 = 1/9
Head Tail 1/3 * 2/3 = 2/9
Tail Head 2/3 * 1/3 = 2/9
Tail Tail 2/3 * 2/3 = 4/9

By the way, the results of 1st and 2nd flips are independent.

answered Mar 17 '11 at 5:02

user6023

fbafelipe · Answer 2 · 2011-03-17 05:02:37Z

up vote 2 down vote

Head Head: 1/3 * 1/3 = 1/9
Head Tail: 1/3 * 2/3 = 2/9
Tail Head: 2/3 * 1/3 = 2/9
Tail Tail: 2/3 * 2/3 = 4/9

answered Mar 17 '11 at 5:02

fbafelipe

migrated from stackoverflow.com Mar 17 '11 at 12:25