okay so there's a new button on your calculator that's not listed in your notes we're going to add right here for problems exactly like this instead of binomial PDF it's binomial cedia the C versus the p is for one point exactly like you're gonna point right at the five right at the three right at the one only one one particular x value the cdfs the C stands for cumulative and it says it finds exactly this probability that we just did it finds the probability of everything from zero up to your value so this would find the probability that X is less than or equal to some number look at the subtle difference when we wanted it to be exactly three we did binomial PDF this is the probability that exactly three tails but if we want three or less we're really saying in this particular problem the same problem we just did you agree this is the problem we were just looking at three or less so then we could have used now that I'm teaching everything why do we do it the long way I just want to make sure you know what it's giving you we could use binomial CDF and binomial CDF does exactly what we just did it takes the three and everything below it all the way down to zero so let's try binomial CDF with the same information here right the N was 10 the P was one-half and the X was three put that into your calculator and see what you get she's over here going uh-huh and I think that that means she must have 1000.172 so it's doing all of this for you did we get 0.172 yeah that's much nicer much more convenient and the reason Partners don't tell you how to do CDF versus pdf I need you to understand what CDF is doing you need to know when to choose PDF and when to choose CDF yes so PDF is for exactly and EDF is for less than or or equal like so if I say probability of no more than seven tails that's seven or less so I would do CDI but if I say the probability of exactly six tails then I would do a pedia did you remember a situation or five or more yes I'll tell you how to do that here in the second time is my question that's your question too yeah and we're going to think compliments to answer those we are man what'd you say oh no no never mind you're sitting back there talk about how much fun you're having is that what it was just thanking God didn't see oh thank you I'm not so sure it was Todd but maybe it was somebody somebody's Direction yeah so I'm very rarely gonna expect you to do these all one at a time but it's I like to do at least one so you understand what the CDF is doing