To express the probability of an event in decimal form, you calculate the ratio of the number of favorable outcomes to the total number of possible outcomes.

Probability quantifies the likelihood of an event occurring. To determine this in decimal form, you must first identify the number of favorable outcomes (the outcomes you are interested in) and the total number of possible outcomes. For instance, consider rolling a fair six-sided die and wanting to find the probability of rolling a 3. In this scenario, there is $1$ favorable outcome (rolling a 3) and $6$ total possible outcomes (rolling any number from $1$ to $6$).

To compute the probability in decimal form, you divide the number of favorable outcomes by the total number of possible outcomes. Thus, you calculate:

This decimal value reflects the probability of rolling a 3 on a six-sided die.

Let’s consider another example: flipping a coin. There are $2$ possible outcomes: heads or tails. If you want to find the probability of getting heads, you have $1$ favorable outcome (heads) and $2$ possible outcomes (heads or tails). Therefore, the calculation would be:

Keep in mind that probabilities in decimal form range from $0$ to $1$, where $0$ indicates that the event cannot occur and $1$ signifies that the event will certainly occur. Using decimal probabilities is often more convenient for calculations compared to fractions or percentages.