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# FQ8

### formula quiz 8

Question | Answer |
---|---|

random variable | is a variable whose value is a numerical outcome of a random phenomenon. there are two types of random variables (discrete and continous) |

a discrete random variable | is a random variable which takes on only a finite or countable number of possible values |

a probability distribution foa rv X | tell sus what the possible values of X are and how porbabilites are assigned to those values (also called probability function) |

a continous random variable x | takes all values in an interval of numbers |

mean of a random variable is | x1p1+x2p2+xnpn |

the variance of this random variable is | sigma (xi-mu)squared pi |

the stanadrd deviation of this random variable is | the square root of the variance |

rules for means ( if x is a random variable and a and b are constants) | mua+x=a+mux, mubx=bmux, mua+bx=a+bmux, mux+y=mux+muy |

rules for variances | var (a+x)=var(x), var(bx)=bsqauredvar(x) |

var (x+y)= | var(x)+var(y) |

var(x-y)= | var(x)+var(y) |

law of large numbers | the difference between a sample proportion and a poporlation propoertion must gegt smaller as the sample size gets larger" |

Created by:
lilee256