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