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 04-09-2011, 10:08 AM #1 (permalink) Moderate your Moderation.   Join Date: Nov 2008 Location: Troy, Pa. Posts: 8,919 Pasta - '96 Volkswagen Passat TDi 90 day: 45.22 mpg (US) Thanks: 1,369 Thanked 430 Times in 353 Posts Math question. 600/12=50, 600/10=60. The difference from 10 to 12 is 2, the difference from 50 to 60 is 10. 11 is 50% of the difference between 10 and 12, 55 is 50% of the difference between 50 and 60... BUT! 600/11=54.54e. Um? __________________ "¿ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı"
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 04-09-2011, 09:04 PM #2 (permalink) Left Lane Ecodriver     Join Date: Aug 2008 Location: Buffalo, NY, USA Posts: 2,257 Prius C - '12 Toyota Prius C Thanks: 79 Thanked 286 Times in 199 Posts I find it helpful to visualize multiplication and division geometrically. Consider rectanges that are 10*6, 12*5, or 11*5.45 to see why your first intuition isn't correct.
 04-09-2011, 11:40 PM #3 (permalink) Moderate your Moderation.   Join Date: Nov 2008 Location: Troy, Pa. Posts: 8,919 Pasta - '96 Volkswagen Passat TDi 90 day: 45.22 mpg (US) Thanks: 1,369 Thanked 430 Times in 353 Posts Its not my intuition, and I wasnt asking a question... Its pointing out that there are inconsistencies in digit math when using percentages compared to integers. Intuition would tell you that since 11 is 50% of the diff between 10 and 12, and the respective solutions for ten and twelve were 50 and 60, the solution for 11 should be 50% of the difference. However, average would-be mathematicians haven't accounted for the scaled increase when using the percentile as an intuitive route to check a solution. 600/11 is, in fact, 54.54e, just slightly less than 50% of the difference between the solution for 600/10 & 600/12, even though 11 is exactly 50% of the difference between 10 and 12. __________________ "¿ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı"
 04-10-2011, 02:16 PM #4 (permalink) Master EcoModder     Join Date: May 2008 Location: Maynard, MA Eaarth Posts: 7,901 Mica Blue - '05 Scion xA RS 2.0 Team Toyota 90 day: 42.48 mpg (US) Forest - '15 Nissan Leaf S Team Nissan 90 day: 156.46 mpg (US) Number 7 - '15 VW e-Golf SEL TEAM VW AUDI Group 90 day: 155.81 mpg (US) Thanks: 3,466 Thanked 2,938 Times in 1,837 Posts Math questions are answered here: http://www.khanacademy.org/ Specifically on percentages: Khan Academy __________________ Sincerely, Neil http://neilblanchard.blogspot.com/
 04-14-2011, 09:44 AM #5 (permalink) aero guerrilla     Join Date: Oct 2008 Location: Warsaw, Poland Posts: 3,640 Svietlana II - '13 Peugeot 308SW e-HDI 6sp 90 day: 58.1 mpg (US) Thanks: 1,190 Thanked 689 Times in 436 Posts Christ, if you were to divide different numbers by the same denominator, then the function would be linear, and proportions would work. But when you divide the same numerator by different denominators the function is now rational, which is governed by its own laws. Percentiles and averages become less intuitive. __________________ e·co·mod·ding: the art of turning vehicles into what they should be What matters is where you're going, not how fast. "... we humans tend to screw up everything that's good enough as it is...or everything that we're attracted to, we love to go and defile it." - Chris Cornell [Old] Piwoslaw's Peugeot 307sw modding thread
 04-14-2011, 01:37 PM #6 (permalink) dude...wait...what?     Join Date: Feb 2011 Location: Cincinnati Ohio Posts: 161 Diesel Rx-7 - '82 Mazda Rx-7 GSL merc 300d - '82 Mercedes-benz 300d dt b2200 diesel - '84 Mazda b2200 D Thanks: 6 Thanked 12 Times in 11 Posts 42 __________________ 82 rx7 diesel 82 300d diesel 84 b2200 diesel All veggie, all the time!
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CarloSW2
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 The Following User Says Thank You to cfg83 For This Useful Post: Joenavy85 (04-14-2011)
 04-14-2011, 04:39 PM #8 (permalink) Making Ecomods a G thing   Join Date: Jan 2011 Location: Illinois Posts: 655 Angie - '08 Infiniti G35 X 90 day: 22.03 mpg (US) Thanks: 35 Thanked 75 Times in 58 Posts C, the answer is always "C" __________________
 04-14-2011, 06:55 PM #9 (permalink) Pokémoderator     Join Date: Dec 2007 Location: Southern California Posts: 5,864 1999 Saturn SW2 - '99 Saturn SW2 Wagon Team Saturn 90 day: 40.49 mpg (US) Thanks: 439 Thanked 530 Times in 356 Posts Christ - I made this plot of denominator increments of 0.1 and the result : The red line is "as if" the result was linear. CarloSW2 __________________ What's your EPA MPG? Go Here and find out! American Solar Energy Society
 04-14-2011, 07:43 PM #10 (permalink) Moderate your Moderation.   Join Date: Nov 2008 Location: Troy, Pa. Posts: 8,919 Pasta - '96 Volkswagen Passat TDi 90 day: 45.22 mpg (US) Thanks: 1,369 Thanked 430 Times in 353 Posts That illustrates the point, Carlos. Thank you. __________________ "¿ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı"