Union apprenticeship sign-ups near Chicago - 5 months and counting

I heard of an apprenticeship with paid on-the-job training for people changing careers. I am in Chicago, in case local advice matters. Applications close in 8 weeks. How hard is the test?

The aptitude test was mostly maths and reading a diagram. Free practice tests online were enough for me.

Visit the training centre in person if you can. Seeing the classrooms helped me decide.