Learn about probability and how it applies in real world. Grade 9 Alberta mathematics curriculum.
Lesson 9.1 of Probability & Statistics in Grade 9 Math — Alberta curriculum lessons.
Probability is the study of how likely an event is to happen. It helps us make predictions about uncertain situations — like whether it will rain tomorrow or if a coin will land on heads.We use probability to describe the chance of something occurring. It's usually written as a fraction, decimal, or percent between 0 and 1: 0 → the event is impossible (it can't happen); 1 → the event is certain (it will definitely happen); Anything in between → the event is possible, but not guaranteed
Theoretical probability is what should happen in theory, based on mathematical reasoning.
Example:
When you roll a fair 6-sided die, the chance of getting a 3 is:
Experimental probability is based on actual results from experiments — what really happens, not just what should happen.
Example:
If you roll a die 60 times and get a "3" 8 times, then:
Probability isn't just about dice, coins, or cards — it's something we use in everyday decisions. We often think about how likely something is to happen, even if we don't write it as a fraction or percent.
For example:.
These are all decisions based on probability — even when we make them instinctively.
Sometimes, we make judgments based on personal beliefs or experiences, not exact data. This is called subjective probability — it's based on what we feel is likely, rather than what the numbers say.
If a basketball player makes 3 out of every 5 shots on average, the theoretical probability of making a basket is 3/5 = 0.6.If, in a game, the player takes 10 shots and makes 4, the experimental probability is 4/10 = 0.4. Over time, with more data, the two values will likely become closer.
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