# 10-6/3 = First Class HonorsMay 20, 2015 2:16 AM   Subscribe

Basically, I need help with a really simple math problem.

So, after a thesis and numerous exams, my very last ultimate final level boss exam is on at the end of the month. And it's a big one. Only, my brain is a bit too fried to work out the math about which docs I should study or not.

So, I have 10 government acts. In the exam, we are going to get a random list of 6 of these, from which we choose 3 to comment on. I would like to get away with studying only 6 docs, not 10 (because right now my brain is so fried, hence why I'm even asking this question).

Is there a scenario where the 6 (random) docs I study do not overlap with the 6 (randomly?) chosen by the examiner? I only need to actually comment on 3 docs at the end of the day. So, if only 3 of my studied docs turn up in the exam, then that's still a win. But it can't be less than three.

I mean, logically, I think I can study 6 - no matter what they are - and at least get asked on 3 in the exam. I think. Right?

(It's painfully obvious that I study history, and not anything remotely quantitative...)
posted by Chorus to Education (4 answers total)

Best answer: You need to study at least 7.

In the worst case, the three you didn't study will be 3 of the 6 on the exam. The other three will be three you did study.
If you only study 6, the worst scenario is that the 4 you didn't study are 4 of the 6 chosen for the exam. That means you only know 2 of the documents. Not enough.
posted by vacapinta at 2:23 AM on May 20, 2015 [10 favorites]

Best answer: Yes, it needs to be 7, because if you only studied 6, then there are *4* you haven't studied. That could mean that out of the 6 questions you get, 4 are unknown acts.
By studying 7, you leave 3 unstudied, so worst case scenario is there are 3 unknown acts out of 6.
posted by EndsOfInvention at 2:28 AM on May 20, 2015 [2 favorites]

Response by poster: Thanks guys - lifesavers!
posted by Chorus at 3:01 AM on May 20, 2015

Often a question can be turned on its head to make it easier to understand. One way to think of this is of how many you can afford to ignore. Of 6 in the exam you can disregard 3, hence you can disregard 3 of the original 10 and so need to study 7. (Makes sense to me.)
posted by epo at 3:42 AM on May 20, 2015 [4 favorites]

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