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Last updated on June 18th, 2025

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Probability

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The study of uncertainty, probability is used to measure the likelihood of the occurrence of an event. It is expressed using numbers from 0 to 1. If the probability is 0, then the event will not happen; if the probability is 1, the event will happen. Probability has applications in fields like statistics, science, and engineering.

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What is Probability in Math?

In mathematics, probability is used to measure the likeliness of the occurrence of an event. The event is represented between the numbers 0 and 1. If the probability is 0, it means the event will not occur. Probability of 1 means the event will definitely happen. 

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History of Probability

The concept of probability flourished during the 17th century. Mathematicians Blaise Pascal and Pierre de Fermat developed the foundation of probability theory while solving problems for gambling. Over time, probability has evolved and played a crucial role in fields like science, economics and artificial intelligence.

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Types of Probability

Probability can be divided into two main types based on the experiments, logic, or past data:
 

  • Classical probability
  • Empirical probability


Let us look at them one by one

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Classical probability

Classical probability is based on the assumption that all outcomes are equally likely in a sample space. For e.g., the probability of rolling a 3 in a fair six-sided die is 1/6

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Empirical Probability

The empirical probability, or most commonly known as experimental probability, is determined by experiments and observations. The probability is calculated as the ratio of favorable outcomes to the total number of trials conducted. 
For example, if a coin is tossed 100 times and lands on heads 55 times, the empirical probability of getting heads is 0.55.
 

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Properties of Probability

There are various properties of probability. Some of the most important properties are given below:


Non-Negativity:

This property states that the probability of an event is always greater than or equal to zero. The mathematical representation is:
P(A) ≥ 0

 


Normalization: 

The property of normalization states that the probability of the entire event or sample space is always equal to 1. The mathematical representation is:
P(S) = 1

 


Additivity: 

The property states that, if 2 events A and B are mutually exclusive, then the events cannot occur at the same time. The probability of either event occurring is equal to the sum of their individual probabilities. The mathematical representation is:
P(A ∪ B) = P(A) + P(B)

 

Complementary Rule: 


This property states that the probability of an event not occurring is 1 minus the probability of it occurring. The mathematical representation is:
P(Ac) = 1 - P(A)
 

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Importance of Probability for Students

Probability is an important concept for students as it helps them develop their critical thinking skills, decision-making skills and analytical skills. Probability helps students get proper understanding of uncertainty, assess risks and make informed decisions for weather predictions, games and financial planning.

 

We use probability in most of our subjects in academics like statistics, data analysis and research. Learning probability will enhance the student’s problem-solving skills, which prepares them for fields like engineering, medicine and artificial intelligence.

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Tips and Tricks to Master Probability

 There are a lot of confusions while solving for probability. Students sometimes get confused when solving problems. To curb these confusions, let us see what kinds of tips and tricks the students can use. The tips and tricks are mentioned below:

 

Understanding the Basics:

Students must first be able to understand the fundamentals of probability like sample space, events and their rules. They must be able to remember the masters, like the formula for classical probability which is

P(A) = Favorable outcomes/Total outcomes

Addition rule: P(A ∪ B) = P(A) + P(B) - P(A ∩ B)

 

Use Tree Diagrams and Venn Diagrams:

The use of tree diagrams and Venn diagrams helps the students to understand sequential probabilities and set-based probability questions.

 

Keep Practicing:

Students must practice solving problems involving probability to understand the concept of probability even better. Practice will make them get some confidence in solving problems quickly and efficiently. This helps the students to get accurate and correct answers.

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Real-World Applications of Probability

Probability can be applied in various real-life scenarios and fields. Let us now see the fields where probability is applied:
 

  • Weather Forecasting:

    We use probability in weather forecasting to predict what kind of weather would be there for the next day.

     
  • Business and Finance:

    In business and finance, probability is used to assess the risk and returns of various types of investments. It is also used to analyze and predict consumer behavior.

     
  • Medicine and Healthcare:

    In the field of healthcare, probability is used to predict the type of diseases based on the symptoms exhibited by patients. 
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Common Mistakes and How to Avoid Them in Probability

Learning and working with probability can be tricky as even small mistakes can lead to errors. Understanding the common mistakes will help us improve accuracy and make better predictions.

Mistake 1

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Ignoring the Total Sample Space

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Students should always make a list of the complete sample space before calculating the probability.

 

For example, when rolling a die, students must note down all the possible outcomes.

Mistake 2

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Misapplying Complement Rule

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Students must always remember the formulas of all the rules of probability, like the complement rule. Understanding and applying the complement rule can help us solve complex problems easily.

Mistake 3

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 Rounding too Early

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Students should practice keeping the numbers if they are in fraction form till the end, as it helps them in getting accurate answers.

Mistake 4

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Assuming Equal Probability for all Outcome

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 Students should not make quick assumptions and must carefully examine the given data.

 

For example, assuming that in a class with 10 boys and 20 girls, picking a random student gives a 50% chance of getting a boy.

Mistake 5

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 Lack of Practice

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Students should always keep practicing the problems related to probability, as it helps them to increase their speed and accuracy in getting right answers.

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Solved Examples on Probability

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Problem 1

What is the probability of getting heads when tossing a fair coin?

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The probability of getting heads when tossing a coin is 50%

Explanation

A fair coin has two equally likely outcomes: heads (H) and tails (T).

The probability of an event is calculated by dividing the number of favorable outcomes by the total number of outcomes:

P(H) = favorable outcomes/Total Outcomes = 1/2 = 0.5 or 50%
 

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Problem 2

What is the probability of rolling a 3 on a fair six-sided die?

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The probability of rolling a 3 is ⅙. 

Explanation

There are six equally likely outcomes in a fair die with 6 faces: 1, 2, 3, 4, 5, and 6.

Hence, the probability of getting a number is the number of favorable outcomes divided by the total number of outcomes.

Hence, P(3) = 1/6 
 

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Problem 3

What is the probability of drawing a heart from a standard deck of 52 cards?

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The probability of drawing a heart from a deck of 52 cards is 25%.

Explanation

A standard deck of cards has 52 cards, out of which 13 are hearts.

We use a formula, where the number of favorable outcomes is divided by the number of outcomes.

Hence, P(H) = 13/52 = 0.25 or 25%
 
 

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Problem 4

What is the probability of getting heads when tossing two fair coins?

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The probability of getting two heads when tossing two coins is 0.25 or 25%

Explanation

 The possible outcomes when two coins are tossed are HH, HT, TH, and TT.

Only one outcome has two heads when the coins are tossed.

Hence, P(HH) = 1/4 = 0.25 or 25%

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Problem 5

What is the probability of rolling a sum of 7 when rolling two fair six-sided dice?

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1/6

Explanation

The combinations that sum to 7 are (1, 6), (2, 5), (3, 4), (4, 3), (5, 2), and (6, 1).

There are 6 favorable outcomes out of a total of 36 possible outcomes.

We can use the formula to find the probability.

Hence, P(sum of 7) = 6/36 = 1/6.
 

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FAQs on Probability

1.What is Probability?

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2.How is probability calculated?

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3.How is probability calculated?

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4.What is the probability of an event not happening?

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5.What is sample space?

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6.What is an event?

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Jaipreet Kour Wazir

About the Author

Jaipreet Kour Wazir is a data wizard with over 5 years of expertise in simplifying complex data concepts. From crunching numbers to crafting insightful visualizations, she turns raw data into compelling stories. Her journey from analytics to education ref

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Fun Fact

: She compares datasets to puzzle games—the more you play with them, the clearer the picture becomes!

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