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Questions and Answers
What does the probability measure?
If a fair coin has equal chances of heads or tails, what is the probability of getting heads?
What defines mutually exclusive events?
Which term refers to the collection of all outcomes outside the original event?
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What is a compound event?
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How is conditional probability defined?
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Which approach involves calculating probabilities based on the ratio of favorable outcomes to total trials?
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What is the total number of possibilities when selecting two distinct cards from a standard deck without replacement?
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How do we calculate theoretical probabilities in experiments following predictable patterns?
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What does the notation $P(AB)$ represent in probability theory?
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Study Notes
Class 12 Mathematics: Probability
In Class 12 mathematics, you'll encounter many fascinating concepts, one of which is probabilityâ€”the calculation of likelihood events will occur based on available data. Here, we'll delve into this crucial subject with a focus on its core ideas and their applications.
Foundational Concepts

Probability: This measures how likely it is that something specific will happen when given a certain set of conditions. It is always represented as a number between 0 and 1 inclusive. For instance, a fair coin has equal chances of getting heads or tails; hence, the probability of either outcome is (\frac{1}{2}).

Sample Space: A comprehensive collection of all possible outcomes of an experiment forms the sample space (S). Each event within the problem must belong to the specified sample space.

Event: An event represents any subset of the sample space that contains outcomes sharing some common characteristics. Events have unique probabilities associated with them. If more than one element belongs to an event, it's known as compound event.

Mutually Exclusive Events: Two events are mutually exclusive if they cannot both happen simultaneously during a single trial. In other words, there can only ever be one winner from such events. Their combined probability equals the sum of individual probabilities.

Complementary Event: The complement of an event is the collection of all outcomes occurring outside the original event. Its probability is calculated by taking the difference between 1 and the probability of the initial event.

Conditional Probability: When information about one event affects our understanding of another event, we refer to conditional probability. Letting (P(AB)) represent the conditional probability of event (A), given event (B).
Calculating Probability
There are several ways to compute probability depending upon the type of experiment being conducted:

Relative Frequency Approach: By calculating the ratio of the frequency of favorable outcomes divided by the total number of trials, we determine relative frequencies and eventually convert these values into probabilities.

Theoretical Probability: Many experiments follow predictable patterns where every outcome has a specific chance of happening. We can calculate theoretical probabilities using simple counting techniques like factorials, combinations, and permutations.
Here's a brief example demonstrating calculating the probability of choosing two distinct cards without replacement from a standard deck:
Let's say we pick two cards randomly out of a standard 52 card deck, without replacing the first selected card before picking the second one. To find the probability of selecting the king of hearts ((K_H)) followed by the queen of clubs ((Q_C)), we need to count the total number of successful outcomes and divide it by the total number of possibilities:
Total successful outcomes = Number of (K_H) cards * Number of (Q_C) cards after removing (K_H) = 1 * 1 = 1
Number of possibilities = Total number of cards  Card chosen initially + Cards remaining after removing chosen card = 51  1 + 51  1 = 100
Now, divide successful outcomes by the total possibilities: [ P(K_H, Q_C)=\dfrac{1}{100}=\frac{1}{%} ] or approximately 0.01.
These foundational concepts equip students well for further explorations in advanced mathematical disciplines such as statistics, probability theory, and machine learning.
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Description
Explore the foundational concepts and methods for calculating probability in Class 12 Mathematics. Learn about sample space, mutually exclusive events, conditional probability, and various approaches like relative frequency and theoretical probability. Master the art of determining probabilities using realworld examples.