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assembly programming, grad school exams

I was so proud that this class I'm taking has me understanding assembly... I did really well on the test and even got full credit on the crazy program we had to write the code for on paper.

new issue though... when I write php, I blank out and can't write do...while loops anymore, I only think in jumps. jump on zero. jump on not zero. jump on rope. whatever. I could never be a programmer.

In other news... my probability test (also a Big Deal) had a question that's still bothering me. It was this: you're expecting a phone call in the next ten minutes. Given the fact that the call will not happen for 5 minutes, what is the probability that the call will happen between 6-8 minutes? [P(6<t<8|t>5)]

After doing a ton of weird poisson crap, I gave up, crossed it out, and put 40%. I feel bad about it. I mean, logically it's a simple question but I've found in this class when I try to think logically I get everything wrong because I'm not that smart. I also know that this is a graduate level course and we spent one week on simple obvious probability stuff and the rest of the unit on distribution/density functions and random variables, so why would he smack an elementary school question on there for 30 points?

I lost confidence in myself over the light bulb problem... there's two boxes of 100 light bulbs, one has 20 defective one and the other has 5, and when we did a practice problem I figured it didn't matter about the boxes, the chances of a light bulb being defective is 25/200. I was wrong... you have to figure there's a 50% chance of picking either box and do the conditional math and it changes all the probability. evidence that I'm not smart, so after I saw that, I lost faith in myself.

is anyone good at math who can make me feel better? or worse? or certain?

Comments

( 10 comments — Leave a comment )
crazyzofo
Oct. 2nd, 2006 03:31 am (UTC)
statistics and college algebra is as far as i have to/am willing to go. i ASSURE you, you are way smarter than i am.
deana_in_texas
Oct. 2nd, 2006 03:34 am (UTC)
My guess is, if it was worth that much and stuck in the middle of the exam rather than at the beginning, that the phone calls were distributed exponentially (meaning poisson rates in between calls) rather than evenly.

If that's the case, you can ignore the 5 minutes (exponential means memoryless) that it can't be in and say it's the same as saying:
You're expecting a phone call in the next five minutes. What is the probability that the call will happen between 1-2 minutes? And you plug in the poisson formula which I've forgotten at the moment and get the answer.

Hope that made sense... I pretty much suck at explaining things.
infinimpulse
Oct. 2nd, 2006 04:15 am (UTC)
WOW. Waaaaay over my head. If it makes you feel any better, I'm struggling to learn basic algebra.
consortofvenus
Oct. 2nd, 2006 04:26 am (UTC)
I'm awful as math. Basic math. Fucking division... even multiplication.
(Deleted comment)
gmalivuk
Oct. 4th, 2006 08:15 pm (UTC)
I find with the Monty Hall problem (and quite a few others, actually) that the best way to illustrate why the probability changes is to strongly exaggerate the situation. (The mathematics alone proves it, but I think this helps people get their minds around it.)

Suppose instead that there were 100 doors, and you knew one of them had the fabulous prize behind it while the other 99 had goats behind them. (I guess we should also suppose that, for you, a goat doesn't count as a fabulous prize.)

You pick one door, the host opens all but one of the other 99. Should you change your guess? Of course you should. When you made that guess, you didn't have any information about where the good prize might be. But now, the host just told you the locations of nearly all the goats.
kart
Oct. 2nd, 2006 08:30 am (UTC)
I flail at math far worse than you do. Srsly.

The assembly vs. php thing made me chuckle tho. That kind of thing happens to everybody.
feanelwa
Oct. 2nd, 2006 09:57 am (UTC)
That's a very confusing question, you're not given any information about the habits of the person calling or anything. I would have said 40% too because, well, what other information are we given?

Probability questions are always a bastard.
daizylibra
Oct. 2nd, 2006 09:50 pm (UTC)
All math is a puzzle of sorts. But, the 'probability' that you'll give a shit about that probabibility class when you're through it is slim to none. That's how I felt anyways. :)
jume
Oct. 3rd, 2006 12:50 am (UTC)
I hate probability.
hydroterra
Oct. 7th, 2006 03:12 am (UTC)
So whats the answer to the lightbulbs one?
( 10 comments — Leave a comment )

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