Flashcards · Maths · Probability
Probability Basics and Relative Frequency
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What is the formula for probability when outcomes are equally likely?
Number of favourable outcomes divided by the total number of outcomes.
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What is the probability of an impossible event?
0.
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What is the probability of a certain event?
1.
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What is \(P(\text{not } A)\)?
\(1 - P(A)\).
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What do all the probabilities in a situation add up to?
1.
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What does mutually exclusive mean?
The events cannot happen at the same time.
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What is the addition rule for mutually exclusive events?
\(P(A \text{ or } B) = P(A) + P(B)\).
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What is the formula for relative frequency?
The number of times an event happened divided by the total number of trials.
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How can you tell if a dice might be biased?
Its relative frequencies are far from the expected \(\dfrac{1}{6}\), especially with many throws.
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How do you find an expected number of outcomes?
Multiply the probability by the number of trials.
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How many outcomes are there for two dice?
36.
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What is the probability of a total of 7 with two dice?
\(\dfrac{1}{6}\).
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What are the outcomes for two coins in order?
HH, HT, TH and TT.
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What is the general addition rule (Higher tier)?
\(P(A \text{ or } B) = P(A) + P(B) - P(A \text{ and } B)\).
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What is the probability of a heart or a king from a pack of cards (Higher tier)?
\(\dfrac{16}{52} = \dfrac{4}{13}\).
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Why does a larger experiment give a better estimate?
Relative frequency gets closer to the true probability with more trials.