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Probability is a mathematical way of describing the likelihood that a certain event will happen, it

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is measured as a number between zero and one where zero means that the event will never happen.

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One will mean that event is absolutely going to happen.

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And any number in between is a measure that the likelihood that the event will happen let P of a B.

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The probability that Event A will occur such that for any event A the probability is between zero and

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one.

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For example, if the probability is point five, then there's a 50 percent chance that the event will

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occur such that on average it will have been half the time that the event is tested.

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So if we have our look at a single coin toss, we can even get a heads or tails showing on the up face

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utmost face.

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So the set of possible events is either heads or tails, and we're going to have a 50/50 chance of getting

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either heads or tails.

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So at this point, five probability of getting heads and a point, five probability of getting tails.

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So if we flip the coin 10 times, it is likely that all heads five times in total and tails five times

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in total.

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And this is on average.

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So if we look at this single toss event, we have a set of heads and tails and we know that there's

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a probability of getting point five for heads and a probability of point five for tails.

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Now, if we sum them up, we're going to get the total probability and this probability is going to

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equal to one.

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So this is saying that if we look at all the different events in the city, we're going to get at least

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one of the events of the set.

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So if we sum up all the events is always going to equal to one.

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And we can write this as this.

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So the sum of all possibilities for each event or outcome in S must equal one.

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So we know that one event has to happen is is impossible not to get any one of those events.

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The probability of event occurring, assuming that each event is equally likely, can be written as

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this probability equation here.

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So the probability of Event A is equal to the number of days event occurs divided by the number of outcomes.

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So if we have a look at tossing two coins, we're going to get a heads, heads, heads, tails, a tale

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head or tail tails, so we have four different outcomes when we toss Cossey two coins so we can work

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out the probability that we're going to get a heads, heads.

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So heads, heads, we're going to get we can get it one way.

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So the number of times we get that A is one number of events instead.

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S is four.

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So one, two, three, four.

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So the probability of getting heads heads is one of the four and we can do that for the same thing for

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all the other probability.

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So probability of heads, tails, tails, heads and tails, tails.

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And if we have a look at this again, we can see that if we suck up all the probabilities here, it

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is going to equal to one.

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So we have to get at least one event out of this set occurring.

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Since we know that the total probability of all outcomes must equal one, then the probability of event

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A not occurring must be given by this relationship here.

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So the probability that Event A does not occur must be the total probability, one minus the probability

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that event occurs.

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So if we look at the example of rolling a single dice, we can even get the outcomes one, two, three,

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four, five or six represented by this set here.

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So the probability of rolling in two must be one of the six.

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There's one way to get a two and there's six different outcomes.

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So the probability of going a two is one of the six.

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We know the probability of rolling any number between one and six must be equal one because it's all

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the different options in the set.

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So then the probability of rolling any number other than a two must be the probability of not getting

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a two is just one minus probability of getting two or one minus or one minus one, six or five, six.

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So the probability of drawing any number of other than two is five over six.

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And we can easily see this from the set up here.

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If we don't if we want to work out the probability of getting a number, that's not a two is just give

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me one, two, three, four, five.

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Divided by the total number, which is six.

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So to summarize, the total probability of a single set is has to equal to one one outcome must happen

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every time we test the four and then the probability of event occurring, assuming that each event is

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equally likely, is given by the number of ways even A can occur divided by the total number of outcomes.

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So if we're talking about flipping a coin, it'll be 50/50 for heads or tails, assuming the age of

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the event is equally as likely.

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So the coin is not weighted, so it doesn't have a higher probability of landing on one or the other.

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If it did, would need a different way of accounting for this and the probability of event A not occurring

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or the probability of not a just equal to one minus the probability of the event occurring.