STATS 250 Lecture Notes - Lecture 5: Standard Deviation, Statistic, Sampling Distribution
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STATS 250 Full Course Notes
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The first discrete example we did was the number of toys played with. Density curve is where the total area underneath the curve is 1 which represents. Area under the curve are related to the probabilities. We did income which was skewed to the right. We also did bell curves called normal distributions. The z-table gives us the area under a normal curve where the mean is 0 and the standard deviation is 1. Let x=# of left-handed in a random sample of 120 americans. X has binomial distribution with n=120 and p=0. 1. Find the probability the sample will contain 20 or fewer lh: P(cid:523)x=(cid:884)(cid:882)(cid:524)=p(cid:523)x=(cid:882)(cid:524)+p(cid:523)x=(cid:883)(cid:524)+ p(cid:523)x=20) however this will be too much work. To draw n(cid:523)(cid:524) graph, we need to know it"s shape which is uniform. Graphing them with sticks and smoothing it out, we get a bell shaped curve so it will be approximately normal so we can find the probability by finding the area under the curve.
