SD from Mean

Question

Oftentimes, the standard deviation is used to understand the dispersion of the data.
We are working with the mtcars dataset and need to find the number of cars that fall into 1 standard deviation from the mean of the mpg column.
This means that we need to find the cars that have the mpg value in the range of mean(mpg)-sd(mpg) and mean(mpg)+sd(mpg).

Answer 1

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Answer 2

mean1 <- mean(mtcars$mpg)
sd1 <- sd(mtcars$mpg)

lowr <- mean1 - sd1
uppr <- mean1 + sd1

in_range <- subset(mtcars, mpg >= lowr & mpg <= uppr, select= c(mpg))
print(length(in_range$mpg))