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Stats: Modeling the World - Bock, Velleman, & DeVeaux
Chapter 14: From Randomness to Probability
Key Vocabulary:
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random phenomenon
trial
outcome
event
sample space
Law of Large Numbers
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1.
In statistics, what is meant by the term random phenomenon?
When we know the outcomes of an event but not when they will happen.
2.
In statistics, what is meant by trial and outcome?
Each occasion we observe a random phenomenon and the value it takes.
3.
What is sample space?
The collection of all possible outcomes; we call this event the sample space.
4.
What does it mean for trials to be independent?
The outcomes of one trial do not affect the outcomes of another trial.
5.
How is the Law of Large Numbers related to probability?
As the number of independent trials increases, the long-run relative frequency of repeated
events gets closer and closer to a single value.
6.
In statistics, what is the probability of an event?
The long-term relative frequency of an events outcome.
7.
What is the Law of Averages?
It is a common misconception that doesn’t exist.
8.
Explain why the probability of any event is a number between 0 and 1.
An event can either not occur with a probability of 0, is certain to occur with a probability
of 1, or the probability of the event occurring lies between the two extremes.
9.
What is the sum of the probabilities of all possible outcomes?
1
independent
probability
empirical probability
personal probability
complement
disjoint
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mutually exclusive
addition rule
legitimate
multiplication rule
independence assumption
Chapter 14: From Randomness to Probability
Stats: Modeling the World - Bock, Velleman, & DeVeaux
10. What is meant by the complement of an event A? Provide a formula.
The set of all outcomes that are not in an event. P A  1 P AC
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11. When are two events considered disjoint?
Events that do not have any outcomes in common.
12. What is the probability of two disjoint events, one or the other?
The sum of the probabilities of the two events. P A  B  P A  P B
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13. What is the Multiplication Rule for independent events?
The probability that both events occur is the product of the probabilities.
P A B  P A  P B
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14. Can disjoint events be independent? Explain.
No. Disjoint events do not have any outcomes in common therefore knowing that one
outcome occurs give insight as to whether the other will occur.
15. Explain the difference between the union and the intersection of two or more events.
Union means one of the events occur; intersection means both events will occur.
Chapter 14: From Randomness to Probability