Compute matrix an data frame : Body mass index (BMI) is a biometric measure of the relationship between height and weight of an individual. The BMI data were compiled in the following vector: imc <- c (18, 19, 24, 25, 30, 35, 30, 20, 18, 15). The criterion of experts to classify the groups is the following: low (<18.55); Normal (18.55-25) and overweight (> 30). With this information create a vector of factors called imcRangos from imc that shows the values, low, normal and overweight.

I need some help with it. 
 I really I do not understand it.

Please.
Thanks