Chapter Hub
Probability
Probability tells us how likely an event is to happen, using a number from 0 to 1. For CBSE Class 10, the chapter begins with simple experiments like tossing coins, throwing dice, drawing balls, and selecting cards, then moves to comparing chances and using complements. The main skill is careful counting. Students must build the sample space correctly, identify favourable outcomes, and apply the formula only when outcomes are equally likely. Most exam errors come from wrong counting, missing outcomes, or mixing up event and complement.
Difficulty
Medium
Study time
96-120 min
Plan by time
Pick the window that matches what you have right now.
If you have 15 min
Last-pass revision
Skim the Quick Revision table — definitions, formulas, and the traps board examiners reuse.
Open Quick RevisionIf you have 45 min
Targeted practice
Read the high-priority concepts, then take the chapter MCQ quiz to find weak spots.
Start MCQ QuizIf you have 96 min
First full pass
Walk every concept in chapter order, then revise and quiz. Best for the first time you study this chapter.
Open Key ConceptsChapter Learning Map
Start with one of the buckets below, then open the full map when you want the complete concept roadmap.
Key Concepts
Concepts grouped the way the chapter is taught — open the bucket that matches what you want to revise.
Core Concepts
high priorityOpen the chapter concepts in a clean revision order.
Probability of an event
Probability of an event is a number that shows how likely that event is to happen.
Equally likely outcomes
Equally likely outcomes are outcomes that have the same chance of happening in an experiment.
Sample space for coin toss
The sample space for a coin toss is the set of all possible outcomes of that toss.
Sample space for die throw
The sample space for throwing a die once is the set of all possible faces that can appear.
Probability as favourable over total outcomes
For equally likely outcomes, probability of an event equals favourable outcomes divided by total outcomes.
Impossible event
An impossible event is an event that cannot happen in a given experiment.
Certain event
A certain event is an event that must happen in a given experiment.
Complement of an event
The complement of an event is the event that the original event does not happen.
Probability in card selection contexts
This is the use of probability when one or more cards are chosen from a deck or a card set.
Probability in spinner or bag contexts
This is probability applied to a spinner or a bag where each sector or item may represent an outcome.
Comparing likelihood of events
Comparing likelihood means deciding which event is more likely by comparing their probabilities.
Checking validity of a probability value
A probability value is valid only if it lies between 0 and 1, including both ends.
Exam Intelligence
Use this section to decide what deserves the most revision time.
High Probability Topics
- Probability of an event
- Equally likely outcomes
- Sample space for coin toss
- Sample space for die throw
- Probability as favourable over total outcomes
- Impossible event
- Certain event
- Complement of an event
Common Traps
- Missing outcomes in the sample space, especially for two coin tosses.
- Using favourable outcomes as the denominator instead of total outcomes.
- Forgetting that the complement adds up to 1 with the original event.
- Comparing fractions by numerator only or denominator only.
- Accepting values greater than 1 or less than 0 as probabilities.
Likely Question Types
- MCQ: concept checks, applications, and common mistakes
- Very short answer: definitions, formulas, or conditions
- Short answer: worked method, example, or reason-based explanation
- Case-based: chapter scenario with concept-linked subparts
Quick Revision
Concept, formula or equation to remember, and the trap that loses marks — in one scannable view.
- Probability measures chance on a scale from 0 to 1.
- Sample space must be complete before calculation.
- Favourable outcomes are the outcomes that satisfy the event.
- Complement means the event does not happen, so use 1 - P(E).
- Card, spinner, bag, coin, and die questions all follow the same counting logic.
- Probability of an event: Probability of an event is a number that shows how likely that event is to happen.
- Equally likely outcomes: Equally likely outcomes are outcomes that have the same chance of happening in an experiment.
- Sample space for coin toss: The sample space for a coin toss is the set of all possible outcomes of that toss.
Practice
Use short concept checks first, then move into the full chapter test.
Free Chapter MCQ Quiz
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