标题: Probability question [打印本页] 作者: Roflnadal 时间: 2013-5-7 03:22 标题: Probability question
Hi everyone,
I was thinking about the statistics involved in passing the CFA exam when I had a thought.
Here’s a hypothetical situation:
There’s an exam with 100 questions, A-B-C with only one correct answere to each question. Suppose, a student is sure of 40 of the questions he answeres, and decides to guesse the remaining 60. Statistically speaking, he will corretly answere a third of the questions he guesses (due to being only 3-choice exam). So, am I correct in thinking, that he will score (in perfect theory) 40 + 1/3*60 = 40 + 20 = 60 questions, scoring 60% on the exam?作者: dirk01 时间: 2013-5-7 03:26
No, he will not score a 60%. That is, instead, his expected score. The expected probability of him guessing correctly is 1/3, so it is likely his score will be around 60%, given that he could answer 40 questions with 100% accuracy. It highly unlikely that his score will be exactly 60%.
