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Cool riddles that supposedly come from Microsoft's interview process:

1. You're outside the door to a room with 3 light bulbs. The door to it is closed. On the wall next to the door are 3 light switches, each corresponding to one of the light bulbs inside. You need to identify which switch goes to which bulb, but once you open the door to look you are not allowed to touch the switches again. How do you do it?
   

   Solution (highlight): If we call the switches A, B, and C, flip on A, wait a minute, then flip off A and flip on B. The warm bulb that is off is A, the one that's on is B, and the one that's off is C.

2. Before you are 2 jars. You have 100 marbles: 50 blue and 50 red. A jar will be picked at random, and then a marble picked at random from that jar. Assuming that every marble is used, how would you distribute the marbles to maximize the chance of getting a red marble? What is that probability?
   

   Solution (highlight): Short version: Put one red marble in the first jar and all the rest in the second jar. Long version: If there are x reds and y blues in jar 1, then the probability of getting a red marble is x/2(x+y) + (50-x)/2(100-x-y). Since y appears in the denominators only, clearly we want y=0. The resulting expression is minimized for x=1 (we can't have both x and y equal to 0 in this formula). The probability in this case is 0.7474 (repeating).

Regarding Julianna's comment on the previous post, my actual dentist didn't tell me that, about the straw-drinking. Fortunately I'm a hypochondriac, so I googled the crap out of it before and after, and discovered that I should avoid straws that way--or else I would certainly have dislodged my clots by now. Although, that would mean that he would get to collect more money from my insurer when I went back. Actually, funny thing: the assistant asked the dentist if he'd like to take some more x-rays, to get a better view of the teeth in question, and he was like, "nah, well, wait, what's her insurance? Oh, Delta? We'd better get those x-rays then." I guess it's nice-ish that if he though I would have to pay out-of-pocket for them that he'd try to forego the additional x-rays, but geez, it makes me really glad I did have good insurance, because even I could figure out that the initial x-rays didn't give a really clear view of all my wisdom teeth. Sucks for poor people.

I really want to poke at them with my tongue. But then I stop myself, because I'm afraid it will hurt or mess up my healing. But I'm really interested in what's going on in there, and I can't figure out how get things arranged to look in there with a flashlight and mirror.

Doesn't really hurt that well, although I Have Been Warned, so I will continue to pop my Advil at regular intervals.

Also scary: eating and brushing my remaining teeth.

Just got my wisdom teeth out (all three of them). I really wish I had brought my iPod--I couldn't feel anything (except the really fucking painful shots in the roof of my mouth, which made my eyes water), but I could hear it--may I never have to hear my teeth being yanked out again. Really. Yuck. Crunchy.

Doot doot, bleeding into my mouth.

So, the other day a guy brought his iPod in for me to look at, because it was misbehaving, and had the most adorable little error screen ever:

Awww.

So anyway. I hooked it up to my Mac, but it wouldn't mount (show up on the desktop), and Disk Utility couldn't see it, although System Profiler recognized that there was an unknown device attached to the firewire port. Disk Warrior couldn't see it either, incidentally. When I turned it on it would just go to the sad iPod screen, then shut itself off. I tried resetting it (hold select + play), to no avail, and couldn't get it into diagnostic mode or disk mode either. Huh. So I did a bunch of googling, and some guy mentioned that his had miraculously recovered well enough for him to get the music off it when he had accidentally knocked it off his desk. He had uploaded a recording of the sound his iPod's hard drive was making, and it sounded quite similar to the clicky noise this iPod was making. Hmmm.

Yes, this is going where you think it is.

I dropped the guy's iPod from about two feet off the ground, and turned it on.

It totally worked after that.