Probability · SS 2
Multiplication rule (AND)
Find the chance of two things both happening when one doesn't affect the other.
- Independent events: P(A and B) = P(A) × P(B)
What the letters mean
- A, B
- two independent events
- independent
- one happening does not change the chance of the other
Worked example
A coin is tossed and a die is thrown. Find P(head and a 6).
Step 1: Multiply
P(head) × P(6) = 12 × 16 = 112
Final answer: 112
Without replacement? The second probability changes: the bag has one fewer item.
See it
Play with this picture from the Probability of Combined Events lesson.
1st ↓ 2nd →
6 of 36 outcomes → P = 636 = 16