Likely Event — Definition, Formula & Examples
A likely event is an event that has a high chance of happening, meaning its probability is close to 1 but not exactly 1.
An event is classified as likely when its probability is greater than and less than , indicating that the event is expected to occur more often than not but is not certain.
How It Works
Probability uses a likelihood scale to describe how probable events are: impossible (0), unlikely (close to 0), equally likely (0.5), likely (close to 1), and certain (1). When you say an event is "likely," you mean its probability falls in the upper portion of this scale, typically above 0.5. For example, if you have a bag with 9 red marbles and 1 blue marble, drawing a red marble is a likely event because its probability is 0.9.
Worked Example
Problem: A spinner has 8 equal sections: 6 are green and 2 are yellow. Is landing on green a likely event?
Find the probability: There are 6 green sections out of 8 total.
Classify on the likelihood scale: Since 0.75 is greater than 0.5 and less than 1, the event falls in the "likely" range.
Answer: Landing on green is a likely event because its probability of 0.75 is close to 1.
Why It Matters
New York State math standards ask students to place events on a likelihood scale from impossible to certain. Understanding the word "likely" helps you describe real-world chances precisely, such as predicting weather or assessing risk in everyday decisions.
Common Mistakes
Mistake: Treating "likely" as the same as "certain."
Correction: A likely event can still fail to occur. Only an event with probability exactly 1 is certain. An event with probability 0.9 will not happen about 10% of the time.