past year solutions from maths society sucks

i dunno y i continue to purchase past year solutions from them, when their solutions are mostly wrong.
the main reason is cause got no other choice, sigh, where else in nus got ppl sell pyp for maths modules one.
update: some questions are also missing from my soln set, wtf? then my fren one even best, the qn there put "forget to do" instead of the soln.