The probability of red is 1/4. What is the probability of not red
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Probability is a measure of how likely an event is to occur. It's expressed as a number between 0 and 1, where 0 means the event is impossible and 1 means the event is certain. For example, if the probability of an event is one-fourth, it means there's a 25% chance of that event happening.
Complementary events are pairs of outcomes that are mutually exclusive and together cover all possible outcomes. For any event A, its complement consists of all outcomes that are not A. The key relationship is that the probability of an event plus the probability of its complement always equals one.
We are given that the probability of red is one-fourth. We need to find the probability of not red. Since red and not red are complementary events, they partition the entire sample space. This means their probabilities must add up to one. We can visualize this with a rectangle where one-fourth is colored red and the remaining portion represents not red.
To find the probability of not red, we use the complementary probability formula. The probability of not red equals one minus the probability of red. Substituting our given value, we have one minus one-fourth. Converting one to fourths gives us four-fourths minus one-fourth, which equals three-fourths. Our visual representation confirms this result, showing that three-fourths of the area is not red.
We can verify our answer using multiple visual models. A pie chart clearly shows the one-to-three ratio between red and not red sections. A spinner divided into four equal sections, with one red and three not red, demonstrates the same probability distribution. A bag containing one red ball and three not red balls also confirms that the probability of not drawing red is three-fourths. All these models consistently verify our calculation.
To summarize, we were given that the probability of red is one-fourth. Using the complementary probability principle, we calculated that the probability of not red is one minus one-fourth, which equals three-fourths. The key takeaway is the general formula: the probability of not A equals one minus the probability of A. This fundamental principle applies to any event and its complement, making it a powerful tool for probability calculations.