7th Grade · Statistics & Probability
Certain Event
7.SP.C.5
Definition
An event that is guaranteed to occur. Its probability is exactly 1 because every possible outcome is favorable.
Examples
- P(rolling a number 1-6 on a standard die) = 6/6 = 1.
- P(drawing a red or black card from a standard deck) = 1 — every card is one or the other.
Key rule
A certain event includes all outcomes in the sample space.
Memory hook
P = 1 means it will definitely happen.