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This 3 page Reader was uploaded by Dauphine Sizer on Monday August 18, 2014. The Reader belongs to a course at a university taught by a professor in Fall. Since its upload, it has received 173 views.
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I'm pretty sure these materials are like the Rosetta Stone of note taking. Thanks Dauphine!!!
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Date Created: 08/18/14
Dauphine Sizer AP Statistics Probability Chapter 11 SRS simple random sample the basics Sum of all probabilities or all possible outcomes is equal to 1 Probability of an event will be between 0 and 1 from a 0 chance to 100 chance but will be written in decimal form for practicality The formula for the probability of an outcome not occurring is 1 minus the probability of the exact opposite the event actually happening for example let s say the chance of the barista at Starbucks spelling your name right is 22 So inversely the chance of her getting it wrong would be 78 This kind of probability only works on a yesno rightwrong kind of situation only two outcomes Disjoint mutually exclusive and independent events what does it a mean really Disjoint Events Disjoint events are the SAM E as mutually exclusive events So we all remember Mean Girls right That vest was disgusting You can t sit with us Well disjoint events are the Plastics How you may ask Well here it is 39 The probability of two disjoint events occurring at the same time is ZERO Regina coudn t wear sweatpants on Monday AND sit with the Plastics at lunch Zero chance Who is she kidding Another example you cannot be both a freshman and a sophomore at the same time These groups are mutually exclusive or disjoint same thing Disjoint PAand B 0 Dauphine Sizer Special Addition Rule This rule ONLY applies when events are DisjointMutuallyExclusive Special Addition P A or B P A P B So read it out The probability of event A or B happening is equal to the probability of A happening plus the probability of B happening Okay so a bunch of statistical probability mumbojumbo right Example The probability ofA being a freshman is 20 The probability of B being a sophomore is 36 Junior 24 Senior 20 If we drew a venn diagram we will draw some later but just imagine this one there would be 4 circles for each group but none overlapping This is disjoint Because there are no overlapping circles if we want to know the probability of being a freshman OIa sophomore all I would have to do is add together both the freshman circle and the sophomore circle right riiiiiiiiight And now you understand disjoint Onward to independent events Independent Events Now that you understand DMEs it will be easier to understand independent events because they are everything that DMEs are not Independent events are events that can overlap and do overlap If we drew a Venn Diagram there would be overlapping sections and Dauphine Sizer So the rule for adding the probabilities of events that aren t special enough to be DME is called the General Addition Flue GenAdd PAorBPAPBPAand B YAAAAY more mumbo jumbo let s talk it out Probability of A or B happening is equal to the probability of A happening plus the probability of B happening and then minus the probability of A and B happening If you think about it in terms of the venn diagram it s the A section the B section the overlapping section The reason we subtract the overlapping section is because we still want those As and Bs in the overlapping section accounted for but just not twice
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