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Description
Flashcards by jennabarnes12387, updated more than 1 year ago
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Created by jennabarnes12387
almost 11 years ago
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| Question | Answer |
| how do you find the mean of a random variable? | sum of all x values times the probability = Ux = E(x)*p(x) |
| a gambler bets 10 dollars on red on a roulette wheel that have 18 red, 18 black, and 2 green slots. Whats his expected return? | 10*(18/38) + (-10)*(20/38) = -0.526 on average the gambler will loose 52.6 cents per bet |
| how do you find the standard deviation of a random variable? | sigma = square root(E(x-u)squared * p(x)) |
| a gambler bets 10 dollars on a specific roulette number. he gets 350 if he wins with an average loss of 52.6 cents a bet. What is the standard deviation? | sigma y = square root((350-(0.53)squared)*(1/38)+(-10 - (0.53))squared * 37/38 = 57.63 |
| what is the probability you will fall into the middle section of a bell curve? | 68% = 0.68 probability |
| What is a Bernoulli experiment? | any experiment that has only two outcomes e.g. yes or no |
| how do you find the probability of the outcomes for a Bernoulli experiment | p(outcome 1) = p p(outcome 2) = 1-p |
| what is the mean of a bernoulli experiment? the sigma? | the mean is p. sigma is found by calculating (p(1-p)) |
| what is a binomial experiment? | a bernoulli experiment performed more then once |
| what do x and n-x equal in a binomial experiment? | x = # of success' n-x = # of failures |
| How do you find the probability of x in a binomial experiment? | (n over x) P to the x (1-p) to the n-x |
| What are the Bernoulli random variables represented as? How do they appear on a number line? | the variables are presented as E1 and E2. E1 becomes 0 on the number line and E2 becomes 1 |
| when you see n over x in brackets, what does it mean? | nCx |
| Suppose that revenue Canada reports that 8% of all tax returns contain errors. An experiment consists of checking errors in a random sample of 10 tax returns. Find the probability that the sample contains exactly one error | P(x=1) = (10 over 1)*0.8^(1)*(1-0.8)^(10-1) = 0.3777 |
| at most one error? | P(x< or equal to 1) = (x=0) + P(X=1) = (10 over 0) * 0.8^(0)(1-0.8)^(10-0) +0.3777 = 0.4344 + 0.3777 = 0.8121 |
| at least one error? | P(x>or equal to 1) = 1-P(x=0) = 1-0.4344 = 0.5656 |
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