How to find variance and std dev in R?

Recipe Objective

How to find variance and standard deviation in R? Variance is the amount of variation/spread in a data set. The standard deviation is the square root of the variance. Standard deviation and variance are needed for conducting many different statistical tests like to calculate the z-score , t-score etc. This recipe illustrates an example of finding variance and standard deviation.

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Step 1 - Define a vector

a <- c(5,10,15,20,25,30)

Step 2- Calculate the mean

print(mean(a)) #using mean()

"Output is ": 17.5 

Step 3 - Calculate the variance

print(var(a)) # using var()

"Output is ": 87.5

Step 4- Calculate the standard deviation

print(sd(a)) # using sd()

"Output is ": 9.354143