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tradingbills/z_score, x_value, empirical rule

Created August 2, 2020 17:54
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z_score, x_value, empirical rule
z_score <- function(x, m, sd){
return ((x-m)/sd)
}
x_val <- function(z, m, sd){
return (z*sd + m)
}
m <- 100
sd <- 15
z_score(130, m, sd)
pnorm(2)
a <- 1 - pnorm(2)
b <- 1 - pnorm(-2)
b - a
1-.9772499
# https://www.youtube.com/watch?v=mai23vW8uFM
# How many people have an IQ above an IQ of 130, where the mean is 100 and the sd is 15
m <- 100
sd <- 15
1 - pnorm(z_score(130, m, sd))
# How many people have an IQ above an IQ of 145, where the mean is 100 and the sd is 15
1 - pnorm(z_score(145, m, sd))
# https://www.youtube.com/watch?v=CjF_yQ2N638&list=PLiIsR5PZj8mvM09Zl5X8CqK8uhUdo1cow&index=2&t=287s 7:46
x_val(1.4, 50, 10)
z_score(30, 50, 10)
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