Probability of Complementary Events & Sample Space

The Organic Chemistry Tutor4 minutes read

The sample space for a 6-sided die includes outcomes 1 to 6, with event A representing outcomes 1 to 4 and event B encompassing outcomes 3, 4, and 5, where the probability of both events occurring is 1/3. Additionally, the chance of selecting a marble that is not red is 65%, derived from a 35% probability of selecting a red marble.

Insights

  • The text illustrates fundamental concepts of probability by detailing how to determine the likelihood of specific events occurring, such as rolling a die where event A includes outcomes 1 to 4 and event B includes outcomes 3, 4, and 5, ultimately leading to a calculated probability of 1/3 for both events happening together.
  • Additionally, the text emphasizes the complementary nature of probabilities, as demonstrated by calculating the chance of selecting a non-red marble, which is derived from the 35% probability of selecting a red marble, resulting in a 65% probability for the alternative outcome.

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Recent questions

  • What is the probability of an event?

    The probability of an event is a measure of the likelihood that the event will occur, expressed as a number between 0 and 1. A probability of 0 indicates that the event cannot happen, while a probability of 1 indicates certainty that the event will occur. Probabilities can also be expressed as percentages, where 0% means impossible and 100% means certain. To calculate the probability of a specific event, you divide the number of favorable outcomes by the total number of possible outcomes. This concept is fundamental in statistics and is widely used in various fields, including finance, science, and everyday decision-making.

  • How do you calculate probability?

    To calculate probability, you need to determine the number of favorable outcomes for the event of interest and divide that by the total number of possible outcomes. The formula is expressed as P(Event) = Number of Favorable Outcomes / Total Number of Possible Outcomes. For example, if you are rolling a six-sided die and want to find the probability of rolling a number greater than 4, you would identify the favorable outcomes (which are 5 and 6) and divide that by the total outcomes (which is 6). Thus, the probability would be 2/6, simplifying to 1/3 or approximately 33%. This method provides a clear and systematic way to assess the likelihood of various events.

  • What does independent events mean?

    Independent events refer to two or more events that do not influence each other’s outcomes. In probability theory, if the occurrence of one event does not affect the probability of another event occurring, those events are considered independent. For example, flipping a coin and rolling a die are independent events because the result of the coin flip does not impact the outcome of the die roll. When calculating the probability of independent events occurring together, you multiply their individual probabilities. Understanding independent events is crucial in probability as it helps in accurately predicting outcomes in various scenarios, from games of chance to statistical analyses.

  • What is a sample space in probability?

    A sample space in probability is the set of all possible outcomes of a random experiment. It encompasses every potential result that can occur when the experiment is conducted. For instance, when rolling a six-sided die, the sample space consists of the numbers 1, 2, 3, 4, 5, and 6. Each of these outcomes is a part of the sample space. Identifying the sample space is essential for calculating probabilities, as it provides the foundation for determining favorable outcomes. By understanding the sample space, one can better analyze and interpret the likelihood of various events occurring within a given context.

  • What is a favorable outcome?

    A favorable outcome is a specific result from a random experiment that aligns with the event of interest. In probability, when calculating the likelihood of an event, favorable outcomes are the results that fulfill the criteria of that event. For example, if you are interested in the event of rolling an even number on a six-sided die, the favorable outcomes would be 2, 4, and 6. The number of favorable outcomes is crucial for determining the probability of an event, as it is used in the numerator of the probability formula. Understanding favorable outcomes helps in making informed predictions and decisions based on statistical analysis.

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Summary

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Probability Calculations for Dice and Marbles

  • The sample space for rolling a 6-sided die includes outcomes 1 through 6; event A includes outcomes 1 to 4, while event B includes outcomes 3, 4, and 5.
  • The probability of both events A and B occurring is calculated as 2 favorable outcomes (3 and 4) out of 6 total outcomes, resulting in a probability of 1/3 or approximately 33%.
  • The probability of selecting a marble that is not red, given a 35% chance of selecting a red marble, is calculated as 1 - 0.35, yielding a 65% chance.
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