About This Worksheet
This worksheet helps twelfth-grade Pre-Calculus students practice reading a discrete probability distribution and finding the probability of a requested event. Students work through six small probability tables and answer questions such as finding the probability of one exact value, values at or below a number, values above a number, or values between two numbers.
The main idea is that students must first identify which outcomes belong to the event and then add the probabilities attached to those outcomes. This gives them practice using a probability distribution as a source of information instead of calculating each probability from scratch.
What Students Practice
Students practice matching a probability question with the correct values of the random variable. If the question asks for exactly one value, they use the probability listed for that value. If the question includes several possible outcomes, they add the corresponding probabilities together.
The worksheet also reinforces wording such as greater than, less than or equal to, and between. Students must read the event carefully before deciding which probabilities to combine.
Why This Skill Matters
Probability distributions are useful because they organize all possible outcomes and their probabilities in one place. Students need to know how to read that information and use it to answer different kinds of questions.
This skill also prepares students for cumulative probability. Instead of focusing on one outcome at a time, they learn how several outcomes can be grouped together into one event.
Common Challenges
Students may include the wrong boundary value. For example, “greater than 2” does not include 2, while “at least 2” does. Encourage students to mark the values that belong in the event before adding anything.
Another common mistake is adding every probability in the table. Students should only combine the probabilities connected to the requested outcomes.
How To Use It
Teachers can use this worksheet after students understand probability notation and valid distributions. It works well for independent practice, homework, or a quick review before expected value.
Parents and homeschool teachers can ask, “Which X-values are included in this event?” Once those are identified, students can simply add the matching probabilities.
Grade Alignment
This worksheet is designed for Grade 12 Pre-Calculus students studying discrete probability distributions. It reinforces event notation, cumulative probability, and reading probability tables.
Students should already understand random variables and probability notation. After this practice, they are ready to calculate expected value.