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Learn it your way
A short class with Sarah and her students. The other ways are under More.
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Today, we're focusing on outcomes. Can anyone tell me what an outcome is in a probability experiment?
I think it's the result of an experiment, like what happens when you toss a coin.
Exactly! So, when we toss a coin, our two possible outcomes are 'Head' and 'Tail'. How do you think we categorize these outcomes?
Could they be categorized as events?
Yes, great observation! Each outcome is indeed an event. So, when we talk about events, we're referring to one or more outcomes from our experiment.
So, in dice throwing, if I roll a '5', that's one event?
Correct! Every number you roll on a die from 1 to 6 is an event. Let's remember: outcomes in experiments are categorized as events!
Now, let’s explore events further. Give me an example of an event related to throwing a die.
How about getting an even number? That would be an event!
Exactly! The even numbers on a die are 2, 4, and 6. So, if I want to calculate the probability of rolling an even number, what would I do?
We'd count the favorable outcomes, which are 3, and divide it by the total outcomes, which is 6. So that's 3 out of 6.
Perfect! So the probability of getting an even number is 1/2. Remember, events can be a single outcome or a collection of outcomes, like getting an even number.
Let's look at how we can calculate the probability of events, using real examples. Can someone give me an event for drawing from a bag with colored balls?
Sure, if there are 4 red and 2 yellow balls, an event would be drawing a red ball.
Correct! Now, what’s the probability of drawing a red ball?
There are 4 favorable outcomes and 6 total outcomes, so that's 4 out of 6.
Right! And how can we simplify that fraction?
It simplifies to 2/3!
Well done! Always remember that understanding combinations of outcomes helps us calculate probabilities effectively!
When you roll a die, take your time, Count numbers and make them rhyme. Every face has its say, Decisions arise in a fun way!
Once a group of friends played a game of dice. Each roll revealed secrets of fate, from lucky sevens to the dreaded snake eyes!
F.O.T. - Favorable outcomes Over Total outcomes to remember how to calculate probability.
P.E.E. - Probability = Events over Outcomes to remember the formula for probability.
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What is an outcome?
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What is an event?
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How is probability calculated?
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This section discusses how individual outcomes of experiments or collections of outcomes are classified as events, illustrating this with examples like tossing a coin or throwing a die.
In this section, the concept of outcomes in probability is introduced, explaining that each outcome of an experiment is considered an event. For instance, outcomes like getting a head when tossing a coin or rolling specific numbers on a die are examples of events and can be quantified for probability calculation.
In probability theory, outcomes are the results of random experiments, while events are collections of outcomes. For example, in the experiment of tossing a coin, the outcomes are 'Head' and 'Tail', and each is regarded as an event. In throwing a die, outcomes include numbers 1 to 6, and events can include getting an even number (events 2, 4, 6). The probability of an event can be calculated by taking the ratio of the number of favorable outcomes that constitute the event over the total number of equally likely outcomes from the experiment. For example, if a bag contains 4 red balls and 2 yellow balls, the probability of drawing a red ball is defined by the favorable outcomes (4) over total outcomes (6). This systematic approach to understanding events and outcomes is crucial in predicting and interpreting results in probabilistic terms.
1.A bag has 5 green balls and 3 black balls. (The balls are identical in all respects other than color.) A ball is drawn from the bag without looking into the bag. What is the probability of getting a green ball? Is it more or less than getting a black ball?
Solution: There are in all outcomes of the event. Getting a green ball consists of 5 outcomes. Therefore, the probability of getting a green ball is . In the same way, the probability of getting a black ball is . Therefore, the probability of getting a green ball is more than that of getting a black ball.
2.A jar contains 4 blue marbles and 6 red marbles. (The marbles are identical in all respects other than color.) A marble is picked from the jar without looking. What is the chance of picking a red marble? Is this chance greater or smaller than that of picking a blue marble?
Solution: There are in all outcomes of the event. Picking a red marble has 6 outcomes. Therefore, the probability of picking a red marble is . Similarly, the probability of picking a blue marble is . Thus, the probability of picking a red marble is greater than that of picking a blue marble.
3.A box contains 8 orange candies and 2 lemon candies. (The candies are identical in all respects other than flavor.) If a candy is chosen from the box without looking, what is the probability of selecting an orange candy? Is this probability more than that of selecting a lemon candy?
Solution: There are in all outcomes of the event. Selecting an orange candy consists of 8 outcomes. Therefore, the probability of selecting an orange candy is . In the same manner, the probability of selecting a lemon candy is . Thus, the probability of selecting an orange candy is more than that of selecting a lemon candy.
4.A crate holds 3 white balls and 7 black balls. (The balls are identical in all respects except color.) If a ball is drawn from the crate without peeking, what’s the probability of getting a white ball? Is it higher or lower than that of getting a black ball?
Solution: There are in total outcomes of the event. Getting a white ball consists of 3 outcomes. Therefore, the probability of getting a white ball is . Likewise, the probability of getting a black ball is . Hence, the probability of getting a white ball is lower than that of getting a black ball.