Index Ai Academy
Glossary · Phase 2 · Math, when you need it

Complement

Everything except the event: the chance something does not happen is 1 minus the chance it does.

The complement of an event is everything else: the event not happening. If 25% of people open your email, the other 75% don't.

Try it now

Work out "none" first, then take it away from 1. Note that it's far less than just adding the chances.

Learn it properly

Probability basics · Events, outcomes and the rules for combining them. About 25 minutes.

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