I believe you are making the same mistake I was making and it took me a while to figure out what I was doing wrong.
Read rule number 3 again. Rule number 3 says that Kate will be the first woman to take the class but not the first student, so we know that before her there will have to be one or more male students in which case it will be N or/and S, because they are the only ones available. See the diagram:
____ -> K -> I+L -> G -> P +ST +ST
MALE. -> O
When performing this diagram, with respect to the rules given to us by the exercise, we observe that we are left with only three variables that can be placed in a less "rigid" way in the diagram: h (female), n (male) and s (male). Thus, we can conclude that N or S will always go before K, since they are the only two males and that with P, consequently, it can never go N + S + P. The only possibilities with P are: P + N/S +H or P + N/S + O or P + O + H.
AsheSeptember 28, 2021
I'm sorry, variable O was supposed to be after variable G. There was a problem when posting.