In this video let’s learn about theoretical probability. Theoretical probability is essentially the chance of something happening, chance of an event occurring. It is not the actual probability because we don’t have any real data, we estimate it. So let’s try it. It says an experiment consists of rolling a fair number cube. A number cube essentially has six outcomes. It can land on one, two, three, four, five or six. We need the find the probability of each event given below.
So in this case when we talk about theoretical probability, probability of an event is essentially the number of ways the event could happen or can occur over the total number of equally likely outcomes, total number of equally likely outcomes. Let’s use the problem given to us as an example. So Part A, probability of ruling a five. How many ways can this event occur, how many ways could five occur. Well there’s only one way that the number of cube can role on and land on a five, so that’s one. Total number of equally likely outcomes, well as we saw there is six possible outcomes each one of them are equally likely.
So the probability of the number of cube landing on a five is 1/6. When we look at Part B, probability of getting an even number, this will become interesting. We’ll be looking at even numbers, one of the numbers of ways the event can occur. Well in this case it can occur one, two and three ways. There are three possible outcomes there are even. The number of ways can be three. One of the total number of equally likely outcomes? Well that still remains the same to be six or 1/2. So the probability of getting an even roll is 1/2 probability of rolling a five is 1/6.
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