Checking validity of a probability value
A probability value is valid only if it lies between 0 and 1, including both ends.
Practice This ConceptMain explanation
Teacher explanation
This rule helps students check whether an answer makes sense. A negative probability is impossible, and a value greater than 1 is also impossible. Every probability in Class 10 should satisfy 0 <= P(E) <= 1, no matter how the event is described.
Example
A probability of 5/4 is not valid because it is greater than 1.
Simple analogy
Probability stays between zero and one.
Common confusion
Students sometimes accept an answer without checking whether it lies in the allowed range.
Exam tip
After solving, quickly test your answer: is it between 0 and 1? If not, recheck the counting.
Answer writing and exam use
1-mark use
Write the exact meaning of checking validity of a probability value in one clean line.
2-mark use
Define checking validity of a probability value and add one example or condition.
3-mark use
Explain checking validity of a probability value, show the method or example, and mention the common mistake.
Practice this concept with focused MCQs
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