Fuzzy logic for clasification

I am trying to implement fuzzy logic system to classifiy dataset of 12 inputs and 1 ouput. I wanna understand as first taks to fuzzify inputs how Can we set intervals or we need to segment inputs first in order to fuzzify them

below is an example of fuzzification but the chose of the intervals is not clear.

Any suggestion or explication will be appreciated

# Generate fuzzy membership functions
qual_lo = fuzz.trimf(x_qual, [0, 0, 5])
qual_md = fuzz.trimf(x_qual, [0, 5, 10])
qual_hi = fuzz.trimf(x_qual, [5, 10, 10])