Similar question to the one above - What is the nature of the position? I understand this is an aptitude test. Does the position you are applying for not require math skills / logic / analytical thinking skills? If not, it seems crazy that they are looking for those skills & aptitudes.
To be honest, if someone tells me that they don't normally do well on these types of questions, they probably don't have the right skill set/aptitude for the job.
After a few years of seeing how unhappy people can be if they are in the wrong job, I've come to believe that its much better for the candidate if they don't get the job when they don't have the right abilities.