**Combined Probability**

When you have two or more events happening in a question:

- Break the question down into a sequence of separate events
- Find the probability of each happening
- Apply the AND/OR rule

**P(Both Events Happen) = AND Rule****P(A and B) = P(A) x P(B)**

So if you need to find the probability of Event A and Event B happening you multiply their separate probabilities together.**Example:** Bag one contains 6 balls, 3 of which are red. Bag two contains 10 balls, 4 or which are red. What is the probability a red ball is picked from both bags?

P(red from both bags) = 3/6 x 4/10 = 0.2**P(At Least One Even Happens) = OR Rule****P(A or B) = P(A) + P(B)**

So if you need to find the probability of Event A or Event B happening you add their separate probabilities together.**Example:** A spinner has a green, red and blue side. The probability of it landing on each side is:

Green – 0.4

Red – 0.5

Blue – 0.1

What is the probability of it landing on green or blue?

P(lands green or blue) = 0.4 + 0.1 = 0.5