exam formula practice Flashcards
(12 cards)
probability distribution expected value equation
E(x) = Σ x*p(x)
x = outcome #
p(x) = probability of x
Σ = the sum of
what is the equation for uniform probability
p(x) = 1/n
n = # of outcomes
what is binomial probability distribution about
to find the # of successes that occures during n trials
what is the binomial probability distribution formula
p(x) = nCr * p^x * q^n-x
q = failure rate
n = # of trials
x = # of successful trials
p = success rate
what is the expected value formula for binomial probability distribution
E(x) = np
p = success rate
n = # of trials
what is geometric probability supposed to find
find the probability of the first success that occures after X amount of trials
-> waiting time is the number of trials before a success
what is the formula for geometric probability
p(x = x) = q^x * p
p = success rate
q = failure rate
n = # of trials
x = n - 1
the best way to find out what value is p and q is to ask yourself what will END the trial - that variable will be “p” because youre failing until you get it right
what is the best way to find out what variables are q and p for geometric probability distribution
ask yourself what will END the trial - that variable will be “p” because youre failing until you get it right
what is the expected value formula for geometric probability distribution
E(x) = q/p
failure rate / success rate
what is the formula for hypergeometric distribution
p(X = x) = (aCx * n-aCr-x) / nCr
n = population size
a = # of successful outcomes in n
X = # of successful outcomes
r = # of trials that are allowed
what is the expected value formula for hypergeometric distribution
E(X) = ra/n
r = dependent trials
n = total
a = success
what is the difference between binomial and geometric
binomial probability is for getting a specific # when you do something specific
geometic probability is for getting a specific # on a certain try
