EXAM 1 Flashcards
σ
standard deviation/ population standard deviation
µ
mean/ population mean
σ2
variance/ population variance
z to find z-score for standard normal
z= (x-µ)/σ
Formula to find z when area between +- Z is given
z= (1- area) /2
N
population size
n
sample size
p
population proportion
p̅
sample proportion
x̅
sample mean
s2
sample variance
s
sample standard deviation
converting to standard normal mean
z= (x̅ - µ)/(σ ÷ √n )
point estimator of µ
x̅
point estimator of s2
σ2
point estimator of p̅
p
sample proportion p̅ formula
p̅ = x /n
sample mean x̅ formula
x̅ = Σ xi / n
sample variance s2 formula
s2 = Σ (xi - x̅)2 / n - 1
standard deviation of p̅ / standard error of p̅
σp̅ = √ p(1 - p)/n
z of p̅ formula
z = (p̅ - p) ÷ σp̅
formula for s (sample standard deviation)
s = (x̅ - µ) /z
or
s = σ/ √n
or
s= √(Σ (xi - x̅)2) / n - 1
Confidence Interval for known σ
CI = x̅ ± zα/2 * σ/√n
Confidence Interval unknown σ
CI = x̅ ± tα/2 * s/√n
E (desired Margin of Error)
E = zα/2 * σ/√n
Range Rule
Range Rule = Range/4
Sample Size for µ (pop. mean) interval estimate.
n = (zα/2)2 * σ2/E2
Interval estimate for p̅
p̅ CI = p̅ ± zα/2 √ p̅(1 - p̅)/n
Margin of Error p̅
zα/2 √ p̅(1 - p̅)/n