Negative marking is not limited to the ratio 1:1, it could be 3:1, 4:1 as the case may be. it will also be wrong to conclude that you get zero if you answer, and correctly, 20 out of 40 questions. you will only be panalized for those you answer wrongly and not those you did not answer at all. did you also notice that some questions did not have their answers among the options. e.g the question about the elevator had , naira as possible answers when the answer should be in hours or minutes. what this means is that in some cases the correct answer is not among the options eventhough in many cases, there is also no option such as "none of the above". the only way to earn the mark here is not to answer the question.