STT 315 Exam 3 Cheat Sheet - *Sample statistic X bar = mean = population parameter = xbar Standard Deviation of sampling distribution(STANDARD ERROR OF

# STT 315 Exam 3 Cheat Sheet - *Sample statistic X bar = mean...

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**Sample statistic X bar = mean = population parameter µ = µ xbar ** Standard Deviation of sampling distribution (STANDARD ERROR OF THE MEAN) = squareroot of sample ¿¿ std.dev .of sampled population ¿ or σ x bar = σ √n Z Score = xbar µ xbar σ xbar Standard Deviation= ( x xbar ) 2 n 1 Confidence Intervals: (α=.20 and α/2 = .10) zscore (Z α/2 )=1.282 = 80% (α=.10 and α/2 = .05) zscore (Z α/2 )=1.645 = 90% (α=.05 and α/2 = .025) zscore (Z α/2 )=1.96 = 95% (α=.01 and α/2 = .005) zscore (Z α/2 )=2.575 = 99% Central Limit Theorem: 1- If a random sample is taken from population with normal distribution then the sampling distribution will be a normal distribution. 2- As the sample size grows large, the sampling distribution will become approximately normal. Sampling Distribution of p^ = mean= σ p^ = standard deviation = ( p ) ( q 1 p ) n Z-Score = p p ( p ) ( q 1 p ) n ------------------------------------------------------------ 100(1-α) % Confidence Interval: Xbar ±(z α/2 ) σ xbar = xbar ± (Z α/2 )( σ n ¿ **We can be 100(1-α) % confident that µ lies  • • • 