STAT 102 Lecture 9: Lecture 9.4docx.docx
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Ex 1: microsoft stock whether or not should invest. Ex 2: advertisement of volvo is confusing are >20% people misled. Ex 3: carnival: box of chips game whether or not is fair. S r p z-score (of proportion) t-score (of sample) Data ( sample ) used to infer something about a population. Context: characteristics of the population ( =mean, =standard deviation, p=proportion in population) Assumptions: each outcome has the same distribution outcomes are unrelated. Central limit theorem: is approx. normal distribution; mean= , standard deviation= / N, 2=p(1-p) p: p is approx. normal distribution; mean=p, standard deviation= ( p (1- p))/ n approximation depends on the size of n and how skewed/non-skewed as n increases, mean of sample approaches mean of population. Ex1: 100 chips, p( >4); is approximately normal, =5, standard deviation=0. 574. P(z>(4-5)/0. 574) = 96: confidence interval : range of plausible values say ; high probability of including true values.
