Question

(Use "mtcars" database) Rstudio

Write a piece of R code to Find the respective variance of “mpg” (miles per gallon) based on the number of “cyl” (cylinders). b) Based on part (a), which number of cylinders (4, 6 or 8) yields the smallest variance in mpg? How large is the smallest variance? [Instruction: you need to present both of the R code and outcomes]

Answer 1

this is the r code for finding the respective variance of “mpg” (miles per gallon) based on the number of “cyl” (cylinders) in mtcars database

**data(mtcars)
names(mtcars)
aggregate( mpg ~ cyl, mtcars, var) **

a) this is the output of above code by rstudio

> data(mtcars)
> names(mtcars)
 [1] "mpg"  "cyl"  "disp" "hp"   "drat" "wt"   "qsec" "vs"   "am"   "gear"
[11] "carb"
> aggregate( mpg ~ cyl, mtcars, var)
  cyl       mpg
1   4 20.338545
2   6  2.112857
3   8  6.553846

b) 6 number of cyllinders yields smallest varience.