When do you add probabilities?
Understand the Problem
The question is asking about the conditions or situations under which probabilities can be combined by addition. This usually involves understanding whether the events are mutually exclusive or not.
Answer
When the events are alternatives (mutually exclusive).
You add probabilities when the events are alternatives (mutually exclusive) and you are calculating the likelihood of either event occurring.
Answer for screen readers
You add probabilities when the events are alternatives (mutually exclusive) and you are calculating the likelihood of either event occurring.
More Information
The addition of probabilities assumes that the events cannot occur simultaneously, meaning they are mutually exclusive.
Tips
A common mistake is to add probabilities of non-mutually exclusive events without considering shared occurrences. Use the formula P(A or B) = P(A) + P(B) - P(A and B) for non-mutually exclusive events.
Sources
- How can I know whether to multiply or add probabilities? - mytutor.co.uk
- In need of tips/suggestions when to add or multiply probabilities - math.stackexchange.com
- How do you know when to add or multiply probabilities? - Quora - quora.com
