Learning basic probability

Learning about basic probability in middle school math

An introductory primer, with the following examples and their solutions assuming there is only one event taking place.

Introduction

Probability can be a tricky concept to understand, especially for middle school students. But don’t worry! With these five clear examples and solutions concerning basic one-event probabilities, you’ll be able to dive into the world of probability with confidence.

Examples with their solutions

Example 1: You have a bag of 10 marbles. 5 are red and 5 are blue. If you draw one marble out of the bag without looking, what is the probability that it will be blue?

Solution: In this case, we know that there are 10 marbles total, and 5 of them are blue. So the probability of drawing a blue marble is 5/10, which reduces to 1/2, or 50%.

Example 2: You have a coin that you flip. What is the probability that it will land on tails?

Solution: In this case, since coins have two sides (heads and tails) and each side has an equal chance of being faced up after flipping, the probability of getting tails is 1/2, or 50%.

Example 3: A jar contains 10 red marbles, 8 blue marbles, 7 green marbles and 6 yellow marbles. If you randomly select one marble from the jar without looking, what is the probability that it will be yellow?

Solution: In this case, there are 31 total marbles in the jar, and 6 of them are yellow. The probability of selecting a yellow marble from the jar is 6/31, or 19%.

Example 4: You roll a die once. What is the probability that you will get an odd number?

Solution: There are six faces to a die, three odd numbers (1, 3, & 5) and three even numbers (2, 4, & 6). So the probability of rolling an odd number is 3/6, which reduces to 1/2, or 50%.

Example 5: You spin an eight-sided spinner once. What is the probability that it will land on 1?

Solution: Spinning an eight-sided spinner means there are 8 possible outcomes (1 through 8). Since we only want it to land on one specific outcome - in this case "1" - then our answer would be 1/8, or 12.5%.

Conclusion

Working through these five examples should give your middle school math student - or yourself! - enough knowledge about probability to feel confident when approaching more complex problems in class or on exams! Plus, understanding how probabilities work can come in handy in everyday life, too! Good luck!