Stats 151 - Random Variables and Probability Mas Function

Question	Answer
What is a Random Variable?	a function of X that associates an unique numerical value with each outcome in the sample (S) e.g. if you toss a coin 2 times, HH = 1, HT = 0, TT = 2, TH = 0
Do the outcomes in a sample have to be numerical?	no. all outcomes will be converted into numbers but they don't have to be numbers to start.
what is a discrete random variable?	the values are discrete meaning that in an isolated area of a number line. e.g. number of siblings in a family can go on forever, but number of boys in a family with 3 children is discrete as there are only 4 possible outcomes; 0, 1, 2, or 3
What is a continuous random variable?	the values of x cannot be counted because they can go on forever or are to large. e.g. waiting time at a clinic can technically go on forever
what is the probability distribution of x?	a list of the values of x and there probability.
how do you find the probability of an event?	sum up all the Pi.
the probability that a sales man will sell 0 item is 0.20, 1 is 0.35, 2 0.15, 3 is 0.12, 4 is 0.10, 5 is 0.05, and 6 is 0.03. what is the probability they will sell at least 3 items?	P(X>3) = 0.12 + 0.10 + 0.05 + 0.03 = 0.30
At most 3 items?	P(X<3) = 0.20 + 0.35 + 0.15 + 0.12 = 0.82
Between 2 and 4?	P(2 < x < 4) = 0.15 + 0.12 + 0.10 = 0.37

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	Created by jennabarnes12387 almost 11 years ago