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Flip to reveal answersWhat is a discrete random variable?
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All 9 Flashcards — Distributions & E(X)
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Question
What is a discrete random variable?
Answer
A variable that takes separate values, each with a probability.
Question
What must the probabilities of a distribution add to?
Answer
1.
Question
How do you find an unknown probability in a distribution?
Answer
Set the sum of all probabilities equal to 1 and solve.
Question
State the formula for E(X).
Answer
E(X) = Σ x·P(X = x).
Question
What does E(X) represent?
Answer
The expected (mean) value — the long-run average of X.
Question
Can E(X) be a value X never takes?
Answer
Yes — it's an average, so it can be a non-outcome value like 2.7.
Question
When is a game fair?
Answer
When the expected net gain E(X) = 0.
Question
How do you find a fair prize?
Answer
Let X be the net gain, set E(X) = 0, and solve for the prize.
Question
What should X be in a game (gain) problem?
Answer
The net gain — include any cost or loss.
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Full study notes for Distributions & E(X)
Topic 4.7 hub
Discrete random variables
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