Simple probability experiments involve identifying possible outcomes, determining whether outcomes are equally likely, and expressing the likelihood of an event as a fraction between 0 and 1. Repeated trials produce experimental probabilities based on observed frequencies, which may vary in small samples but generally become closer to theoretical probabilities as trials increase; conditional probability, dependent events, and formal statistical inference are not included.
To conduct a simple probability experiment:
Example: Rolling a fair number cube
Suppose you want to find the probability of rolling an even number.
Step 1: List the possible outcomes.
A number cube can land on:
Step 2: Check whether the outcomes are equally likely.
Because the number cube is fair, each number has the same chance of being rolled.
Step 3: Identify the favorable outcomes.
The even numbers are:
There are favorable outcomes out of total outcomes.
Step 4: Find the theoretical probability.
So, the theoretical probability of rolling an even number is .
Step 5: Try the experiment.
Roll the number cube times. Suppose the results are:
The even numbers occur times.
The experimental probability is:
The experimental probability, , is close to the theoretical probability, . They do not have to be exactly the same because a small number of rolls can have unusual results. If you roll the cube many more times, the experimental probability will generally get closer to .
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