Picking a correct answer in a multiple choice test answering randomly I was reading a book about techniques to pass a multiple choice test and I found a passage that seems strange to me.
Every question has 5 possible answers, you get 1 point for each correct answer, 0 for each not given answer and -.25 for each wrong answer. 
The book reasoning was like this:

if you choose your answers randomly you have a probability of 1/5 to
  get the correct answer, so if you randomly answer five question, one
  will be correct.

I feel something is wrong about this deduction. I mean, since the each question will be different, how could you be sure that randomly answering five questions will get you one correct answer? 
I think the correct deduction would be something like this:

if you choose your answers randomly you have a probability of 1/5 to
  get the correct answer, so if you randomly answer the same question for five times, you will get the correct answer with one of your answers.

The question is: is the deduction contained in the original passage from the book correct from a probabilistic standpoint?

No, it's technically incorrect as you can't say "one WILL be correct." It should read something like "you are expected to get one fifth of the questions right"
However, if I may deduce where the author is going with this, he will probably say something of the sort "So, you will get one question right (+1) and four incorrect answers (-1), in total you get 0 points. This way, it doesn't matter if you completely guess or skip a question. etc etc". If the book is following this reasoning, the conclusion is correct, even though the poor wording.
