Create and manipulate a data frame. i) Create a `data. frame` named `my. trees` that has the following columns: - `
Girth = c(10.3, 10.6, 10.8, 13.5, 13.7, 13.8, 14.0)` - `
Height = c(70, 65, 63, 72, 81, 83, 66)` - `
Volume = c(10.3, 10.3, 10.2, 16.4, 18.8, 19.7, 15.6)`
ii) Extract the second observational unit.
iii) Extract the `Height` column referring to it by name.
iv) Print out a data frame of all the observations except for the firt observation.