Independent and Dependent Events

Independent Events Two events are independent if the outcome of one event does not affect the outcome of a second event Example: each time I flip a coin I still have a 50/50 chance of getting heads or tails.

Dependent Events Two events are dependent if the outcome of the first event affects the outcome of the second event. Example: If I take a marble out of the jar and don’t put it back in, I change the probability for the next pick.

Formula for Independent Event P(A and B) = P(A) x P(B) The probability or rolling a 4 on a number cube is 1/6. The probability of rolling a 4 on a second cube is also 1/6. The probability of rolling 2 fours becomes 1/6 x 1/6 or 1/36

Formula for Dependent Event P(A, then B) = P(A) x P(B after A) You have five pairs of socks in a drawer in five colors. The probability of picking a blue pair on day one is 1/5. The next day there are only 4 pairs left. The probability of picking the white pair is now 1/4 Probability of blue then white is 1/5 x 1/4 = 1/20