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find the probability of pulling a yellow marble from a bag with three yellow to red to green and one blue I'm assuming marbles so they say the probability I'll just say P for probability the probability of picking a yellow yellow marble and so this is sometimes the event in question right over here is picking the yellow marble I'll even write down the word picking and when you say probability it's really just a way of measuring the likelihood that it's something is going to happen and the way we're going to think about it is how many of the outcomes from this trial from this picking a marble out of a bag how many meet our constraints satisfy this event and and how many possible outcomes are there so let me write the possible outcomes right over here so possible possible possible outcomes and you'll see it's actually a very straightforward idea but I'll just make sure that we understand all the words that people might say so the set of all the possible outcomes well there's three yellow marbles so I could pick that yellow marble that yellow marble or that yellow marble that yellow marble these are clearly all yellow there's two red marbles in the bag so I could pick that red marble or that red marble there's two green marbles in the bag so I could pick that green marble or that green marble and then there's one blue marble in the bag there's one blue marble so this is all the possible outcomes and sometimes this is referred to as the sample space sample the set of all the possible outcomes fancy word for just a simple idea that the sample space if when I pick something out of the bag and that picking out of the bag is called a trial there's eight possible things I can do so when I think about the probability of picking a yellow marble I want to think about well what are all of the possibilities well there's eight possibilities eight possibilities for my trial so the number of outcomes number of possible outcomes you could view it as the size of the sample space number of possible outcomes and it's as simple as saying well look I have eight marbles and then you say well how many of those marbles meet my constraint that satisfy this event here well there's three marbles that satisfy my event there's three outcomes that that will allow this event to occur I guess is one way to say it so there's three right over here so a number that satisfy satisfy the the event or the constraint right over here so it's very simple ideas all many times the words make them more complicated than they need to if I say what's the probability of picking a yellow marble well how many different types of marbles can I pick well there's eight different marbles I could pick and then how many of them are yellow well there's three of them that are actually yellow