STA 261 Exam 3 Cheat Sheet

# STA 261 Exam 3 Cheat Sheet - STA 261 Exam 3 Cheat Sheet...

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STA 261 Exam 3 Cheat Sheet Kimberly Glennon -Binomial Random Variable : fixed # of trials, each trial independent, each trial have 2 possible outcomes, constant prob. of success. -Can we use normal approximation for binomial X? Yes if passes Rule of Thumb: np>10 and n(1-p)>10. -n trials, with k number of successes: n! / x!(n-x)! times p^x(1-p)^n-x --# of possible outcomes that have exactly x successes out of n -Mean of X = np, SD of X = Square Root of np(1-p). THIS IS ALL FOR DISCRETE RANDOM VARIABLES. NOW ONTO CONTINUOUS… -total area under the Probability Density Curve is always equal to 1. Shape determined by mean, spread by SD. (68-95-99.9 rule) -to find how many SDs/standardize(z-score) — (Value-Mean) / (SD) and locate in table. -Continuity Correction: add or subtract 0.5, improves normal approx. If want under #, add 0.5. If wasn’t over #, subtract 0.5. -Sampling Distributions : focus on difference between values of a variable for a sample and its values for the entire population.
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