Mock Exam vs Sample Exam

Today I got an email from CFA Institute touting both the mock exams and sample exams they offer. I’m guessing the same people who write their ethics questions wrote the email because the wording was rather confusing and vague. Does anyone know what the difference is? And do these include explanations?

The CFAI website is your friend. The sample exams are $40 and Mock are $60 !! But they clearly mention that neither of them cover all the topics. There are three different versions that a person would have to take to cover everything… ANYBODY took the sample exam yet? How is it?

I mean the ‘FREE’ one??