CHAPTER 7 Random Variables Saluda County Schools：7章隨機(jī)變量S縣學(xué)校

1、chapter 5:discrete probability distributions5.1 probability distributionsrandom variablesa random variable is a variable whose value is a numerical outcome of a random phenomenon. let x = number of heads. if we get hhth, x = 3 if we get ttth, x = 1 what is the sample space for x?random variables the

2、y are variables because they keep changing they are random because we dont know the next value the variable will assume. we do know the overall pattern of the values assumed by a random variable over many repetitions.random variables a discrete random variable has a countable number of possible valu

3、es. usually countsrandom variables a continuous random variable can take any value in an interval of the real number line. usually measurementsouncesdiscrete orcontinuous? weight of a book number of chapters in a book number of defects in a square yard of fabric number of homeruns in a season weight

4、 of a boat-load of fishdiscrete random variables we will use capital letters to represent discrete random variables usually x or y corresponding lower case letters will represent values of the random variable. p(x = x) is the probability that the random variable x equals the value x.discrete random

5、variables the probability distribution of x lists the values and their probabilities.value of xprobabilityx1p1x2p2x3p3xkpk every pi is between 0 and 1. the sum of the ps is 1.discrete random variables find the probability distribution for a gender for a family with three single births.number of boys

6、probability0123 express p(at least two boys) in terms of x. find it.discrete random variables create a probability distribution for rolling a six sided die.discrete random variables 25% of women cannot distinguish between the colors red and green. find the probability distribution for 3 randomly cho

7、sen women. so, what is the probability that exactly two women will be colorblind? what is the probability that at least one will not be colorblind?discrete random variables create a probability distribution for the following: the probabilities of a return on an investment of 1000, 2000, 3000 are , , and respectively. discrete random variables create a probability distribution for the following: a die is we