Mathematics
Grade 11
15 min
Introduction to probability
Introduction to probability
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1
Introduction & Learning Objectives
Learning Objectives
Define fundamental probability terms including experiment, sample space, event, and outcome.
Calculate the theoretical probability of a simple event.
Understand and apply the rule that the probability of any event is a value between 0 and 1, inclusive.
Calculate the probability of the complement of an event.
Apply the addition rule to find the probability of two events, distinguishing between mutually exclusive and non-mutually exclusive cases.
Differentiate between theoretical and experimental probability.
Construct a sample space for a compound experiment, such as rolling two dice or flipping three coins.
What are the chances of winning the lottery versus being struck by lightning? 🎲 Probability is the mathematics that helps us answer questions about...
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Key Concepts & Vocabulary
TermDefinitionExample
ExperimentAny procedure or action that can be repeated and has a well-defined set of possible results.Flipping a coin, rolling a standard six-sided die, or drawing a card from a deck.
Sample Space (S)The set of all possible outcomes of an experiment.For rolling a single die, the sample space is S = {1, 2, 3, 4, 5, 6}.
Event (E)A specific outcome or a subset of outcomes from the sample space.When rolling a die, the event 'rolling an even number' corresponds to the subset E = {2, 4, 6}.
Theoretical ProbabilityThe probability of an event based on mathematical reasoning and calculation, assuming all outcomes are equally likely.The theoretical probability of rolling a 3 on a fair die is 1/6, as there is one favorable outcome out of six possible outcomes.
Experim...
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Core Formulas
The Basic Probability Formula
P(E) = \frac{\text{Number of favorable outcomes}}{\text{Total number of outcomes}} = \frac{n(E)}{n(S)}
Use this formula to calculate the theoretical probability of an event E, where all outcomes in the sample space S are equally likely.
The Range of Probability
0 \le P(E) \le 1
The probability of any event E is always a number between 0 and 1, inclusive. A probability of 0 means the event is impossible, and a probability of 1 means the event is certain.
The Complement Rule
P(E') = 1 - P(E)
The probability that an event will not occur is 1 minus the probability that it will occur. This is often easier than calculating the probability of the complement directly.
The General Addition Rule
P(A \cup B) = P(A) + P(B) - P(A \cap B)...
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Challenging
For two events A and B from the same sample space, P(A) = 0.7, P(B) = 0.4, and P(A ∩ B) = 0.2. What is P(A ∪ B)?
A.1.1
B.0.5
C.0.1
D.0.9
Challenging
A spinner has sections for Yellow, Green, and Blue. The probability of landing on Yellow is 1/2, and the probability of landing on Green is 1/3. What is the probability of landing on Blue?
A.1/3
B.1/4
C.1/5
D.1/6
Easy
In the context of probability, what is the term for the set of all possible outcomes of an experiment?
A.Event
B.Sample Space
C.Outcome
D.Experiment
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