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# 2 standardize find the z scores using zx meansd and

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Unformatted text preview: i.e. between µ-3σ and µ+3σ). More precisely [but you just need to remember the rounded values 68 , 95 & 99.7] Eg. Standard normal Curve Example: SAT SCORE v༇  Verbal SAT scores for college-bound seniors in 1999 have approximately normal distribution with µ = 505 and σ = 110. q༇  What is the proportion of scores below 615? Example (cont.) Start by drawing a picture Example (cont.) Note: 615 is 1 SD above the mean. (615 = 505 + 110) Want this area: Example (cont.) 68 % 16 % 16 % 395 505 615 Answer = 16% + 68% = 84% Useful property of normal distributions: The Z Score If variable X is normally distributed with mean µ and standard deviation σ, then the variable Z Z= X −µ σ is normally distributed with mean 0 and standard deviation 1 (standard normal). Z-Score & Key consequen...
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