The DW Math Thread

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  • Decus - Dreamweaver
    Decus - Dreamweaver Posts: 5,033 Arc User
    edited June 2012
    not sure where to post this decus :((
    but i cant find my toons nothing shows up on log in screen :((

    missing my 105 wiz my 104 bm my 104 sin :((

    sorry for posting here dont know how to start a new thread :((

    "New Thread" button on the upper left side of the forum.

    Either way, you bumped my thread, so no big deal. I ought to post new problems for this week.
    Proving that not only archers do math since 2009. b:victory
    Current math challenge: pwi-forum.perfectworld.com/showthread.php?t=1029711&page=45
    [SIGPIC][/SIGPIC]
    "Any skills that can be used to kill you will interrupt BB when successful." -truekossy | "...Sage archers are kind of like Mac owners. They are proud of the weirdest and most unnecessary things." -Aesthor | "We ALL know Jesus doesn't play PWI. He may have suffered a lot for humanity, but he'd NEVER punish himself this way." -Abstractive | "I approve of bananas." -SashaGray
  • SSCaster - Lost City
    SSCaster - Lost City Posts: 51 Arc User
    edited June 2012
    I hate word problems, oh so much b:faint


    Can I haz number problems instead?
  • Elanxu - Dreamweaver
    Elanxu - Dreamweaver Posts: 521 Arc User
    edited June 2012
    the loser fail nab cleric from dreamweaver who quit pwi, but still wanders the forums.
  • Decus - Dreamweaver
    Decus - Dreamweaver Posts: 5,033 Arc User
    edited June 2012

    Thanks Elan, nice to chat with you again.

    That being said, just posting two this time because I feel like it. (Trying to avoid brute-force problems, but these are both pretty easy anyway.)

    i

    Anna, the older twin, was born three hours before her younger sister Lana. On Lana's 21st birthday, they both went out to a club with some friends. The bouncer was checking ID's and let Lana go in. But when the older Anna tried to follow her in, the bouncer said, "I'm sorry, your 21st birthday isn't for another two days." How is this possible? Explain fully and correctly.

    ii

    At least a dozen ants are marching through my kitchen! If the ants walk in rows of 7, 11, or 13, there are 2 ants left over, while in rows of 10, there are 6 left over. What is the smallest number of ants there could be?




    Enjoy! Also, happy June 4th!
    Proving that not only archers do math since 2009. b:victory
    Current math challenge: pwi-forum.perfectworld.com/showthread.php?t=1029711&page=45
    [SIGPIC][/SIGPIC]
    "Any skills that can be used to kill you will interrupt BB when successful." -truekossy | "...Sage archers are kind of like Mac owners. They are proud of the weirdest and most unnecessary things." -Aesthor | "We ALL know Jesus doesn't play PWI. He may have suffered a lot for humanity, but he'd NEVER punish himself this way." -Abstractive | "I approve of bananas." -SashaGray
  • Elanxu - Dreamweaver
    Elanxu - Dreamweaver Posts: 521 Arc User
    edited June 2012
    At least a dozen ants are marching through my kitchen! If the ants walk in rows of 7, 11, or 13, there are 2 ants left over, while in rows of 10, there are 6 left over. What is the smallest number of ants there could be?

    im gona take an uneducated guess

    since in multiples of 10, theres 6 left over, the number has to end in 6. if 6 has 2 left over, then the number that would be a multiple of 7,11,13 ends in 4. idk but i think the least common multiple of 7,11, and 13 is 1001, so to make that end in a 4, u multiply it by 4 to get 4004. then u add back the 2:

    4006

    was i anywhere close?
    the loser fail nab cleric from dreamweaver who quit pwi, but still wanders the forums.
  • Yorkin - Dreamweaver
    Yorkin - Dreamweaver Posts: 271 Arc User
    edited June 2012

    i

    Anna, the older twin, was born three hours before her younger sister Lana. On Lana's 21st birthday, they both went out to a club with some friends. The bouncer was checking ID's and let Lana go in. But when the older Anna tried to follow her in, the bouncer said, "I'm sorry, your 21st birthday isn't for another two days." How is this possible? Explain fully and correctly.


    Well, I'd say it is the usual twin paradox from Einstein's Relativity Theory and can be explained thru dilatation of time. Although, I am not sure if there is enough data to calculate it with Lorentz transformations... and then again... I don't think it is that complicated. b:chuckle
    [SIGPIC][/SIGPIC]

    A small tribute to elven mathematician from a human physicist. b:pleased

    Yorkin - The Retired Wizard
  • breeeezy87
    breeeezy87 Posts: 0 Arc User
    edited June 2012
    Thanks Elan, nice to chat with you again.

    That being said, just posting two this time because I feel like it. (Trying to avoid brute-force problems, but these are both pretty easy anyway.)

    i

    Anna, the older twin, was born three hours before her younger sister Lana. On Lana's 21st birthday, they both went out to a club with some friends. The bouncer was checking ID's and let Lana go in. But when the older Anna tried to follow her in, the bouncer said, "I'm sorry, your 21st birthday isn't for another two days." How is this possible? Explain fully and correctly.

    ii

    At least a dozen ants are marching through my kitchen! If the ants walk in rows of 7, 11, or 13, there are 2 ants left over, while in rows of 10, there are 6 left over. What is the smallest number of ants there could be?




    Enjoy! Also, happy June 4th!

    i. They were both born on a non leap year. Anna was born 3hrs or less before midnight on february 28th, therefore Lana was born into the next day on March 1st. They go to the club on Feb. 28th 21 years later, since it's a leap year the days go 28,29,1. Therefore the 1st(Lana's bday) is in 2 days.

    ii. 11*4+2=46
    10*4+6=46
    46 ants \o/
  • Elanxu - Dreamweaver
    Elanxu - Dreamweaver Posts: 521 Arc User
    edited June 2012
    breeeezy87 wrote: »
    i. They were both born on a non leap year. Anna was born 3hrs or less before midnight on february 28th, therefore Lana was born into the next day on March 1st. They go to the club on Feb. 28th 21 years later, since it's a leap year the days go 28,29,1. Therefore the 1st(Lana's bday) is in 2 days.

    ii. 11*4+2=46
    10*4+6=46
    46 ants \o/

    hmm, for number 1, anna was the one who wasnt allowed in, not lana.

    and for #2, 46-2 is not divisible by 7 or 13.
    the loser fail nab cleric from dreamweaver who quit pwi, but still wanders the forums.
  • Decus - Dreamweaver
    Decus - Dreamweaver Posts: 5,033 Arc User
    edited June 2012
    im gona take an uneducated guess

    since in multiples of 10, theres 6 left over, the number has to end in 6. if 6 has 2 left over, then the number that would be a multiple of 7,11,13 ends in 4. idk but i think the least common multiple of 7,11, and 13 is 1001, so to make that end in a 4, u multiply it by 4 to get 4004. then u add back the 2:

    4006

    was i anywhere close?

    Nicely done, Elan. 4006 is correct.
    Well, I'd say it is the usual twin paradox from Einstein's Relativity Theory and can be explained thru dilatation of time. Although, I am not sure if there is enough data to calculate it with Lorentz transformations... and then again... I don't think it is that complicated. b:chuckle


    It isn't, but I like your reasoning anyway! :D
    Proving that not only archers do math since 2009. b:victory
    Current math challenge: pwi-forum.perfectworld.com/showthread.php?t=1029711&page=45
    [SIGPIC][/SIGPIC]
    "Any skills that can be used to kill you will interrupt BB when successful." -truekossy | "...Sage archers are kind of like Mac owners. They are proud of the weirdest and most unnecessary things." -Aesthor | "We ALL know Jesus doesn't play PWI. He may have suffered a lot for humanity, but he'd NEVER punish himself this way." -Abstractive | "I approve of bananas." -SashaGray
  • Yorkin - Dreamweaver
    Yorkin - Dreamweaver Posts: 271 Arc User
    edited June 2012
    Well, I can't help myself. I am a physicist, not mathematician :D
    [SIGPIC][/SIGPIC]

    A small tribute to elven mathematician from a human physicist. b:pleased

    Yorkin - The Retired Wizard
  • zzrxes
    zzrxes Posts: 2 Arc User
    edited June 2012
    breeeezy87 wrote: »
    i. They were both born on a non leap year. Anna was born 3hrs or less before midnight on february 28th, therefore Lana was born into the next day on March 1st. They go to the club on Feb. 28th 21 years later, since it's a leap year the days go 28,29,1. Therefore the 1st(Lana's bday) is in 2 days.

    I go with that theory - you just forgot to mention the fact that in their haste to reach the club, Lana and Anna switched their IDs by mistake.. Since they are twins, the bouncer didn't notice. b:pleased
  • Shawnita - Dreamweaver
    Shawnita - Dreamweaver Posts: 76 Arc User
    edited June 2012
    math makes me b:spit
  • Decus - Dreamweaver
    Decus - Dreamweaver Posts: 5,033 Arc User
    edited June 2012
    math makes me b:spit

    Your fascinating and intellectually stimulating opinion is noted.
    Proving that not only archers do math since 2009. b:victory
    Current math challenge: pwi-forum.perfectworld.com/showthread.php?t=1029711&page=45
    [SIGPIC][/SIGPIC]
    "Any skills that can be used to kill you will interrupt BB when successful." -truekossy | "...Sage archers are kind of like Mac owners. They are proud of the weirdest and most unnecessary things." -Aesthor | "We ALL know Jesus doesn't play PWI. He may have suffered a lot for humanity, but he'd NEVER punish himself this way." -Abstractive | "I approve of bananas." -SashaGray
  • truekossy
    truekossy Posts: 7,021 Arc User
    edited June 2012
    Mind if I bump this? I hope not because me posting this is gonna end up bumping it before you can answer.
  • Decus - Dreamweaver
    Decus - Dreamweaver Posts: 5,033 Arc User
    edited June 2012
    truekossy wrote: »
    Mind if I bump this? I hope not because me posting this is gonna end up bumping it before you can answer.

    I adore you, you know that? b:cute

    I'll have this week's problems posted tomorrow. Too busy right now to attend to it.
    Proving that not only archers do math since 2009. b:victory
    Current math challenge: pwi-forum.perfectworld.com/showthread.php?t=1029711&page=45
    [SIGPIC][/SIGPIC]
    "Any skills that can be used to kill you will interrupt BB when successful." -truekossy | "...Sage archers are kind of like Mac owners. They are proud of the weirdest and most unnecessary things." -Aesthor | "We ALL know Jesus doesn't play PWI. He may have suffered a lot for humanity, but he'd NEVER punish himself this way." -Abstractive | "I approve of bananas." -SashaGray
  • Escorian - Dreamweaver
    Escorian - Dreamweaver Posts: 2,802 Arc User
    edited June 2012
    [SIGPIC][/SIGPIC]
    ty Nowitsawn

    Everything has its beginnings, but it doesn't start at one. It starts long before that... The world is born From zero. The moment zero becomes one is the moment the world springs to life. One becomes 2. 2 becomes 10. 10 becomes 100. taking it all back to one solves nothing. so long as zero remains... One.. Will eventually grow to 100 again.
  • truekossy
    truekossy Posts: 7,021 Arc User
    edited July 2012
    This necro is totally legit and should not be closed.
  • Runemine - Dreamweaver
    Runemine - Dreamweaver Posts: 572 Arc User
    edited July 2012
    ofc math is here to stay........just not for me i got my B in college algebra im done with it for now =P
    101 Blademaster(Pro/Fail 4.0 BM with 11k base HP+G16(+10))
    100 Seeker(The Vortex Beast)
    86 Assassin(Solo king)
    76 Archer(Squishy Nuker)
    72 Cleric(Horrible healer)
    67 Barb(Buff baby)
    61 Wizard(King Aoe)
    37 Mystic(Fun project)
  • Decus - Dreamweaver
    Decus - Dreamweaver Posts: 5,033 Arc User
    edited July 2012
    Damn I keep forgetting to post problems. I swear I will get to it... when I am done packing /o\
    Proving that not only archers do math since 2009. b:victory
    Current math challenge: pwi-forum.perfectworld.com/showthread.php?t=1029711&page=45
    [SIGPIC][/SIGPIC]
    "Any skills that can be used to kill you will interrupt BB when successful." -truekossy | "...Sage archers are kind of like Mac owners. They are proud of the weirdest and most unnecessary things." -Aesthor | "We ALL know Jesus doesn't play PWI. He may have suffered a lot for humanity, but he'd NEVER punish himself this way." -Abstractive | "I approve of bananas." -SashaGray
  • Decus - Dreamweaver
    Decus - Dreamweaver Posts: 5,033 Arc User
    edited October 2012
    Thanks to Nariin for reminding me to update this. These are sort of easy because I was lazy in finding problems and have been far too busy to keep up with them as it stands. I really like number 2 so whoever solves that gets brownie points from me. Also, it may seem like there isn't enough information in some problems, but I assure you there is.

    Voila!

    1. Give me two different numbers, each of which is the square of the other.

    2. An elastic strip of length 1m is attached to a wall and the back of a car. A fly starts at the wall and crawls on the strip towards the car, which at the same time drives away from the wall at a speed of 1m/s. Assuming that the strip can be stretched infinitely long, will the fly ever reach the back of the car?

    3. Suppose a circular hole was drilled through the center of a sphere. When the length of the hole was measured along its wall, it was found to be six inches long. What is the volume of the part of the sphere that remains after the material is removed from the hole? Express your answer as an exact real number number of cubic inches.
    Proving that not only archers do math since 2009. b:victory
    Current math challenge: pwi-forum.perfectworld.com/showthread.php?t=1029711&page=45
    [SIGPIC][/SIGPIC]
    "Any skills that can be used to kill you will interrupt BB when successful." -truekossy | "...Sage archers are kind of like Mac owners. They are proud of the weirdest and most unnecessary things." -Aesthor | "We ALL know Jesus doesn't play PWI. He may have suffered a lot for humanity, but he'd NEVER punish himself this way." -Abstractive | "I approve of bananas." -SashaGray
  • truekossy
    truekossy Posts: 7,021 Arc User
    edited October 2012
    Yay for the thread living again!

    Number two made me giggle from the mental image alone.
  • Mooooooooo - Lost City
    Mooooooooo - Lost City Posts: 377 Arc User
    edited October 2012
    Thanks to Nariin for reminding me to update this. These are sort of easy because I was lazy in finding problems and have been far too busy to keep up with them as it stands. I really like number 2 so whoever solves that gets brownie points from me. Also, it may seem like there isn't enough information in some problems, but I assure you there is.

    Voila!

    1. Give me two different numbers, each of which is the square of the other.

    2. An elastic strip of length 1m is attached to a wall and the back of a car. A fly starts at the wall and crawls on the strip towards the car, which at the same time drives away from the wall at a speed of 1m/s. Assuming that the strip can be stretched infinitely long, will the fly ever reach the back of the car?

    3. Suppose a circular hole was drilled through the center of a sphere. When the length of the hole was measured along its wall, it was found to be six inches long. What is the volume of the part of the sphere that remains after the material is removed from the hole? Express your answer as an exact real number number of cubic inches.

    You packed for 2 months :O

    1.
    -1/2 + sqrt(3)/2 i
    -1/2 - sqrt(3)/2 i

    2. yes. regardless of the fly's speed. suppose the speed is S, it will reach the car after e^(1/S) seconds.

    3. This makes it sound like the size of the sphere does not matter, and after visualizing it, it does seem to be true. Easy way to solve it, hole has 0 radius. so the volume of the remaining sphere is just a whole sphere with radius 3. So the answer is 36pi.

    oh and yeah these were a bit easier, but more interesting imo. the random calculus poo makes me >:
    youtube channel: youtube.com/user/chezedude
  • Decus - Dreamweaver
    Decus - Dreamweaver Posts: 5,033 Arc User
    edited October 2012
    You packed for 2 months :O

    Well no, I packed and then moved to a new city. Keeping up with the thread kinda fell by the wayside >.<

    You nailed all three problems as usual and way before anyone else had a chance to even read them :P I am not posting new ones till next week >:(


    Where is fiz?
    Proving that not only archers do math since 2009. b:victory
    Current math challenge: pwi-forum.perfectworld.com/showthread.php?t=1029711&page=45
    [SIGPIC][/SIGPIC]
    "Any skills that can be used to kill you will interrupt BB when successful." -truekossy | "...Sage archers are kind of like Mac owners. They are proud of the weirdest and most unnecessary things." -Aesthor | "We ALL know Jesus doesn't play PWI. He may have suffered a lot for humanity, but he'd NEVER punish himself this way." -Abstractive | "I approve of bananas." -SashaGray
  • Mooooooooo - Lost City
    Mooooooooo - Lost City Posts: 377 Arc User
    edited October 2012
    Well no, I packed and then moved to a new city. Keeping up with the thread kinda fell by the wayside >.<

    You nailed all three problems as usual and way before anyone else had a chance to even read them :P I am not posting new ones till next week >:(


    Where is fiz?

    he no get on now. maybe once a month. o.O
    youtube channel: youtube.com/user/chezedude
  • CeliaZ - Sanctuary
    CeliaZ - Sanctuary Posts: 901 Arc User
    edited October 2012
    You packed for 2 months :O

    1.
    -1/2 + sqrt(3)/2 i
    -1/2 - sqrt(3)/2 i

    2. yes. regardless of the fly's speed. suppose the speed is S, it will reach the car after e^(1/S) seconds.

    3. This makes it sound like the size of the sphere does not matter, and after visualizing it, it does seem to be true. Easy way to solve it, hole has 0 radius. so the volume of the remaining sphere is just a whole sphere with radius 3. So the answer is 36pi.

    oh and yeah these were a bit easier, but more interesting imo. the random calculus poo makes me >:

    How did you get the formula for 2?
    [SIGPIC][/SIGPIC]
  • Mooooooooo - Lost City
    Mooooooooo - Lost City Posts: 377 Arc User
    edited October 2012
    How did you get the formula for 2?

    magic cow told me.
    youtube channel: youtube.com/user/chezedude
  • CeliaZ - Sanctuary
    CeliaZ - Sanctuary Posts: 901 Arc User
    edited October 2012
    magic cow told me.

    Im seriously interested, I cant figure it out... If you want to tell me I would be really happy.
    [SIGPIC][/SIGPIC]
  • Mooooooooo - Lost City
    Mooooooooo - Lost City Posts: 377 Arc User
    edited October 2012
    Im seriously interested, I cant figure it out... If you want to tell me I would be really happy.

    speed of the fly is S. What you care about is the fraction of the rope the fly moves across rather than some absolute distance. For example, when the rope is scretched to 2m, it would be as if the fly is moving at speed of 1/2 * S.

    so this "speed" decreases with respect to time S' = 1/t * S, where t starts at 1. So you integrate 1/t * S with respect to t, from 1 to x, so that it will sum to 1m (meaning distance of 1 original rope length). Solving for x gives you that formula.
    youtube channel: youtube.com/user/chezedude
  • Sirrobert - Dreamweaver
    Sirrobert - Dreamweaver Posts: 3,395 Arc User
    edited October 2012
    speed of the fly is S. What you care about is the fraction of the rope the fly moves across rather than some absolute distance. For example, when the rope is scretched to 2m, it would be as if the fly is moving at speed of 1/2 * S.

    so this "speed" decreases with respect to time S' = 1/t * S, where t starts at 1. So you integrate 1/t * S with respect to t, from 1 to x, so that it will sum to 1m (meaning distance of 1 original rope length). Solving for x gives you that formula.

    My head now hurts b:surrender
    9 out of 10 voices in my head say I'm not crazy... the 10th is singing the music of tetris
  • Decus - Dreamweaver
    Decus - Dreamweaver Posts: 5,033 Arc User
    edited October 2012
    Im seriously interested, I cant figure it out... If you want to tell me I would be really happy.

    Since the integral of S/t is the natural log (the fundamental "formula" for speed is distance/time), it follows that the solution will be its inverse (the exponential function).
    Proving that not only archers do math since 2009. b:victory
    Current math challenge: pwi-forum.perfectworld.com/showthread.php?t=1029711&page=45
    [SIGPIC][/SIGPIC]
    "Any skills that can be used to kill you will interrupt BB when successful." -truekossy | "...Sage archers are kind of like Mac owners. They are proud of the weirdest and most unnecessary things." -Aesthor | "We ALL know Jesus doesn't play PWI. He may have suffered a lot for humanity, but he'd NEVER punish himself this way." -Abstractive | "I approve of bananas." -SashaGray
This discussion has been closed.