How to create a new variable based on the values of another variable

General
2

You could do something like this

library(dplyr)

your_dataframe_name <- your_dataframe_name %>% 
    mutate(gre_class = case_when(
        gre < 440 ~ "Low",
        gre > 440 & gre < 580 ~ "Medium",
        gre > 580 ~ "High"
    ))

If you need more specific help, please provide a proper REPRoducible EXample (reprex) illustrating your issue.