Discrete Random Variable- Week 8

Random Variable

you can measure, count, categorize

2 Types of Random Variable

1. discrete - finite - has a end/limit to it

   countably infinite - flips until 100 heads

2. Continuous-uncountably, infinite, time goes forever

Difference Btw Discrete and Continuous

discrete - Sum

Continuous - use integral

Probability Distrubution of Discrete Variable

“ how often we expect them to occur”

p(x)

2 Rules of the prob. distrubution

“Is p(x) a legitimate prob distribution “

1. be btw 0 and 1

2. must sum to 1

Pay attention to question?

P(x>3) ——-draw # line

P(x=4) ———given on table, no calucuations

Discrete Random Variable - Mean

Sum( x*p(x)

X Bar NOT EQUAL TO Mx

X Bar - average of a sample

Mx- average of population

The mean should be btw the range of the

the ranges given at top #

Linear Transformation

y=a(Mx)+b

Rule 2

Mx+y

Mx-y

Variance Of Discrete

Sum(x-Mx)square root *p(x)

no units

Standard Deviation of discrete

square root of variance

If X and Y are independent, then True/False:  Variance of (X-Y) = Variance of (Y-X)

true