TypeError: unsupported operand type(s) for /: 'str' and 'float' when trying to pass interperpolate

Question

Code:

cols = ["e_tbhiv_prct", "e_tbhiv_prct_lo", "e_tbhiv_prct_hi", "e_inc_tbhiv_100k", "e_inc_tbhiv_100k_lo"