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John Salerno

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Posts posted by John Salerno

  1. Hi everyone. I just got a game for the Nintendo Switch called Menseki Genius, which has Area Maze puzzles in it. I've been staring at the very first puzzle for quite a while, and I'm stumped. Attached is an image of it.

    My initial figuring was that since the rectangles with areas 11 and 13 are prime numbers, their lengths and widths have to be 11x1 and 13x1, respectively. Working from there, I figured out some other sides, like the other side of the 22cm rectangle being 2, etc.

    But this isn't making complete sense, because that would make one of the sides of the 20cm rectangle 12, which has to be wrong.

    I've tried looking up how to solve these puzzles, but every example I've seen so far shows the puzzle with some of the full side lengths being revealed as well, but this puzzle in question doesn't show those. It only shows the areas of the rectangles.

    What am I doing wrong? How should I be approaching this?

    (FYI: no fractions or decimals are used, and the proportions are not necessarily visually accurate)

    Here is the image. The numbers in blue notes are my own guesses and are not a part of the original puzzle.


  2. 43 minutes ago, fiveworlds said:

    Check if you are using the US/UK keyboard

    I don't understand what you mean. I am using a US keyboard, but why does that matter? I am typing in the proper letters one at a time. Not sure what else I need to check.

    I'm only able to respond to your post because once again I had to reset my password and re-login that way. I've also noticed that the sign in page is not a secure site, which doesn't seem especially safe to me.

  3. Hi everyone. I'm having some trouble logging into the forums. Every time I try, it says my password is incorrect. I've used Chrome to remember the password, and I've also typed it in myself to be sure it's right, but it never works.

    I have reset the password twice already and that usually automatically logs me in, but when I return later I'm logged out again, and logging back in results in the same problem, even though I know for sure that I am putting in the right password.

    I've now reset the password for a third time and am back in, but I know when I return later tonight, I'll be logged out and won't be able to log back in until I reset it again.

    Any ideas on how to fix this?



  4. 4 hours ago, Prometheus said:

    I can't think of an easier way. Subtracting the probability of an event not occurring from 1 is a pretty standard way of finding the probability of an event so kudos for thinking it up.

    Thanks! Just wanted to make sure I was learning how to do it the proper way, and not taking detours like you mentioned in the other thread! :)

  5. Hello everyone. I've got another probability puzzle that I actually did solve, but I feel like I may have taken a longer route than necessary to arrive at the solution. I'm wondering if there is a simpler, more elegant way to solve it than the "backwards" approach I took.

    Basically, the problem is that you have 40 cards remaining in a deck, with all four aces still in the deck. If you draw two cards, what is the probability that exactly one card will be an ace?

    I didn't know how to solve it directly, so I thought it would be easier to find the probability of *both* cards being an ace and the probability of *neither* card being an ace, and subtract those amounts from 1:

    1 - ( (4/40) * (3/39) ) - ( (36/40) * (35/39) )

    This works, and I understand why it does, but it feels like more of a brute force method. Is there a way to directly solve for the probability of only one card being an ace?


  6. 8 hours ago, Prometheus said:

    You've found the solution to a slightly more difficult problem: the probability of a particular colour match. But here we don't care about the particular colour, only that they match.

    It is a bit odd for it to mention 'uniformly' but you seem to have understood it correctly: all it means is that each sock has an equal chance to be chosen. I would have assumed that anyway - but maybe someone objected that they were different sized socks or something. I agree that choosing the second sock would be a dependent event for the problem you have answered. I think it is a subtle clue to the question you should be answering.


    Thank you! After thinking about your comments for a few minutes, I finally figured it out! It was mainly your first sentence that led me to the answer!

    But I'm still a little confused about why it says to assume both events are independent. Isn't the second choice necessarily dependent on the first event?

  7. Hello everyone. I downloaded a puzzle app from the Play Store that has probability puzzles, and I hate to admit I'm already stuck on the second puzzle! But I feel like I'm doing it correctly, though it says my answer is incorrect. I'm just looking for some general guidance for if I'm on the right track. I don't want the answer or a direct solution. If I'm wrong, a suggestion for certain keywords I could search for and read up on would be helpful too.

    Here is the puzzle:



    Six individual socks are sitting in your drawer: two red, two blue, and two purple. It's dark -- you can't see a thing.

    You pick a first sock uniformly at random, and then a second sock from the remaining five. Assume the two choices are independent.

    What's the probability you end up with two socks of the same color?


    First off, I'm wondering if the word "uniformly" means something that I'm not aware of. I've never studied probability, so perhaps that's one aspect I'm missing. Second, even though it seems like drawing the second sock would be a dependent event, I don't understand why it says "Assume the two choices are independent." Maybe this is another thing I'm getting wrong.

    At any rate, I figure the answer is:

    probability of drawing a sock of one color the first time * probability of drawing a sock of the same color the second time = 1/3 * 1/5 = 1/15

    But that doesn't seem to be correct. Any advice or subtle hints?


  8. The answer to your questions is more difficult than it may seem. It is helpful to think of light as a wave that is partially reflected and refracted by the surface of each side of the rain drop. Similar to how light is both partially reflected and refracted when you look into the surface of a pond. Especially on a bright day, you can see a faint reflection in water, but you also still see through the water. However, this is an oversimplification and leads to intuitive problems such as those you have identified.


    What is actually going on is a little more difficult to explain. The photons interact with the electrons throughout the water, and the probability of the path each photon takes can be understood using quantum electrodynamics. I highly suggest that you read Feynman's QED: The Strange Theory of Light and Matter, particularly chapter 2. You should be able to find it at a local library or on Amazon, or alternatively, you can read it free online at Scribd.


    If you wish, you can also watch videos of the four lectures that inspired the book. The second video corresponds to the second chapter in the book.


    Thanks. I've actually been searching for a good intro book to the subject of light, and so far I found this one: http://www.amazon.com/Introduction-Light-Physics-Vision-Color/dp/048642118X/ref=wl_it_dp_o_pC_S_nC?ie=UTF8&colid=2SSP0D0OTC6WF&coliid=I2KL719QS7RFGJ


    Feynman's book was an option, but I felt it might be a little too heavy for a basic introduction, although I do plan to read it eventually as well. I'll at least check out the videos for now, but I have to admit, as much as I've read about quantum mechanics, I still have a little "huh?" question mark over my head every time. :)

  9. I was reading about how rainbows are formed in Richard Dawkins' book "The Magic of Reality," and basically it was described as such: light passes through the upper part of the outside of the drop of water (that is in the air) and then reflects off the interior of the back of the drop and then exits the lower part of the drop.


    My question is, why does the light seem to react differently to different parts of the water drop? In other words, why does the light pass through (rather than reflect off of) the upper part of the outside of the drop? Why does the light reflect off the inside of the back of the drop (rather than pass through the drop, in the same way that it entered it)? Finally, why does the light then pass through the lower part of the drop (rather than reflect off of it, as it did off the back of the drop)? To put it one more way, why doesn't the light either always pass through the water drop, or always reflect off of it, rather than do both at different parts of the drop?


    Hope that makes sense!




  10. I've had many discussions with people about homeopathy and deep into the discussion i realized they had no clue as to what homeopathy meant. I think there is wide spread confusion about what homeopathy is and to some extent i would be willing to bet it's intentional.


    Most people I've talked to seem to think it means natural or organic or some other less than accurate term. When I see homeopathic I read horse feathers...


    That's why I asked my question. I don't understand why the word would be used on a box of throat lozenges that don't seem to be actual homeopathic medicine as I understand it in the technical sense.

  11. I'm glad somebody brought this up, because I've wondered the same thing. Even people who subscribe to alt/herbal medicine seem surprised when I've told them to technical definition of 'homeopathic'


    Yes, when I asked the pharmacist about the lozenges and mentioned that it said "homeopathic" on it, she said "That just means it's used to help prevent an illness." Clearly not the technical definition of the word. So I began to wonder if this is a secondary definition, or if perhaps it's a more palatable definition being used to "hide" the true meaning.

  12. I'm aware of the main usage of the word, i.e. alternative medicine based on the principle that a severely diluted substance which causes the symptoms of the disease to be cured will cure that particular disease. However, my eye doctor suggested I take some vitamins (A, C, and E) and some zinc lozenges to help with my current eye infection. The point was that the vitamins might help shorten the duration.


    But when I found the lozenges in the store, I noticed that the box said "homeopathic" on it, but it didn't seem like a regular homeopathic treatment like you typically see in those little bottles that contain pills. These were supposedly real throat lozenges that claimed to help prevent or cure the common cold. I was skeptical at this point so I decided to skip them, but I'm curious about the use of "homeopathic" in this case. Does it mean something different in certain contexts? It didn't seem to mean the same thing as the above definition about diluted substances.



  13. I think it's safe to say that ie; irritated/inflamed areas of an eye from a viral infection are more susceptible to bacteria.


    Just tell your doctor the situation and get treated for all of 'em. 2 weeks seems like a long time :S


    According to the information I've read, it can even last longer than two weeks. But it's obvious that most of my symptoms are going away, like redness and irritation. I'm basically left with the swollen eyelids and discharge now, which my eye doctor said is normal at this point. It definitely took a while to START getting better at all, though.

  14. I'm not a medical professional, but this reminds me of the two major types of pneumonia, viral and bacterial, where the infection by one can weaken the lungs and lead to the opportunistic infection by the other. Eyes, like lungs, are very exposed to the environment.


    A patient could be infected by one, and be diagnosed as such and likewise treated, and then develop the opportunistic infection by the other, which is then transmitted to another patient.


    So, I'm supposing that someone diagnosed with bacterial pink eye could transmit viral pink eye to you (because they ended up with both, with the one beaten down with medication, but not the other).


    Make sense?


    That makes sense, but does pink eye work that way, like pneumonia?

  15. didn't you get cultures done to confirm the bacterial diagnosis? Anyway, its difficult to tell from symptoms alone what the microbial source could be (you need a more discriminating test).


    Just an opinion from a non-medical professional, if its been two weeks and its not getting better confirming/IDing the source might benefit you by informing treatment options. OTOH, maybe 2+ weeks is not unusual for pink eye. How have other members of your family fared?


    No, I didn't have any tests done to confirm it. I doubt most doctors think it's worth the effort.


    My sister and brother-in-law both seemed to recover within days of starting their antibiotics. The same with my nephew, so perhaps his was bacterial as well. I hope so since the doctor gave him antibiotics. I think my niece's condition lasted longer, about a week or so, so it's possible hers was viral.


    It's entirely possible that all cases in the family are bacterial and I was just misdiagnosed as viral (by one doctor, since their opinions were the opposite of one another), but all my symptoms seem to indicate viral (to my layman understanding, at least). So that's why I asked my question. I was wondering if the viral and bacterial versions are two completely separate conditions (which I would think they are) or if exposure to one can lead to the other. Because it confuses me why we would all have different types...

  16. I'm currently in week two of conjunctivitis, originally diagnosed as bacterial by my general doctor and then later diagnosed as viral by my ophthalmologist. Based on my symptoms and what I've read on WebMD, etc. I'm inclined to think it's viral. I took antibiotic eye drops (prescribed by my doctor) for about 3 days before seeing my ophthalmologist, who advised me to stop using them and instead prescribed corticosteroid eye drops meant to help with the inflammation and irritation. (Those don't seem to be doing much good either.)


    Anyway, all of that is just to ask my question. My niece had pink eye a week before I got it, so I assume I caught it from her. Shortly after I got it, it showed up in my nephew, and then both of their parents as well. As far as my sister and brother-in-law, they actually had tests done that determined their version to be bacterial. We don't know for sure which version my niece had. I assume she's the one who spread it to all of us.


    So I'm wondering, is it possible for the bacterial version to be caught from exposure to the viral version, and vice versa? If my ophthalmologist is right and I do have the viral version, then how could I have gotten that if my niece had bacterial? Or if my niece also had viral, how did my sister and brother-in-law get the bacterial version?


    I suppose we could have gotten it from two separate sources, but it seems likely that it was from my niece.




    There's also this book meant for the parents of said children: "Raising Freethinkers: A Practical Guide for Parenting Beyond Belief" by Dan Barker as well. Again, didn't read this book myself but I heard good stuff about it. You could probably find more through the recommended section in that page.



    I'm reading this book right now. Just want to note the author is not Dan Barker. :)

  18. Oh, and a very good authority says 'The Grand Design' is a sell-out and not up to the standard of his previous books ( I haven't read it yet myself ), and you'd be better served by the Feynman lecture series ( which I have read and are excellent ).


    I don't know who that "authority" is, but thus far I'm finding the book to be very similar to A Briefer History of Time. It covers a lot of the same material, but it also discusses M-theory in more depth (which I think is the topic of the next chapter I have to read). I guess it depends on what is meant by "sell-out."

  19. Gah, I really want to wrap my head around this but it just doesn't make sense! I've read these replies, I've read Wikipedia, I'm currently reading "The Grand Design," but I still don't understand this concept (from Wikipedia):


    The uncertainty principle states a fundamental property of quantum systems, and is not a statement about the observational success of current technology.


    I just don't see how the uncertainty principle is anything other than a description of the problems with measuring techniques, rather than an inherent property of the system being measured. I fully understand how measuring a particle's position, for example, will affect it's momentum, but that still seems like a problem with current measurement technology rather than with the properties of the particle itself. Why isn't it the case the particle still really does have a specific position and momentum, and the problem is simply that we cannot measure them both simultaneously? I don't understand why the uncertainty principle HAS to mean that a particle never has a specific position and momentum at any given time.


    Finally, in reading "The Grand Design," a distinction seems to be made between the uncertainty principle and the idea that measuring something will necessarily change it. Are these two different ideas, or are they the same thing? I thought that the uncertainty principle was basically saying if you measure one thing, it changes something else. But the book seems to be suggesting these are two distinct ideas in quantum physics.



  20. keep in mind that velocity and position are determined relative to the position of the observer. The uncertainty principle highlights this relativity to framer of reference and practically shows that there is no other frame of reference that is relatively in inertia with reference to other frames of references. In this sense, then, getting consistency and precision in the measurement of the position and velocity of a body is determined by its relative consistency with the integral of that due to other frame of reference. This is the underlying truth of the Uncertainty principle.


    And for determinism, it is simply trumped by time relativity and orbits. Hawking did not dismiss this concept by terming it in the supernatural domain...he only accepted his limit. There is what i call back timing...this is what time use to trump all form of determinism...it creates an unending constant change. Keep in mind that this change is relative to the perspective of the observer....and position and velocity are measure with the human time...to me this is a really narrow time frame.


    Hmm, but you seem to be framing the discussion of determinism (or lack thereof) within general relativity, which preceded the uncertainty principle. Are you suggesting that GR and the UP are saying the same thing about determinism? It seems to me that the UP is making a much stronger claim about uncertainty and non-determinism than the consequences of GR suggest.

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