alleryStart learning →The chance of an event plus the chance of its complement always adds to what?
AExactly zero
BExactly two
CExactly a half
DExactly one
Answer & Solution
Correct answer: D. Exactly one
1. The complement of an event holds every outcome that is not in the event.
2. Between them, an event and its complement cover the whole sample space.
3. So their two chances always add up to one.
_Source: OpenStax High School Statistics (CC BY 4.0), Ch 2 "Descriptive Statistics" and Ch 3 "Probability Topics", section 3.1 Terminology_
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