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What two conditions must a table of x and P(x) values satisfy to count as a discrete probability distribution function?
AEach x value is positive and x values sum to one
BEach P(x) equals 0.5 and x values are all distinct
CEach P(x) is in [0,1] and the P(x) values sum to one
DEach x is an integer and P(x) values are all equal
Answer & Solution
Correct answer: C. Each P(x) is in [0,1] and the P(x) values sum to one
1. A discrete PDF table lists every outcome x alongside its probability P(x).
2. Two characteristics must hold: every P(x) sits between zero and one inclusive, and the P(x) values sum to one.
3. Only option A states both requirements correctly.
4. Options A, B, and D substitute conditions on x itself or invented equal-probability rules that never actually appear.
_Source: OpenStax Introductory Statistics (CC BY 4.0), Ch 4 "Discrete Random Variables", section 4.1 Probability Distribution Function (PDF) for a Discrete Random Variable_
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