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1. I had a similar issue in the fifth grade of elementary school (in my country, elementary school is 6 years with an extra year at age about 5 before pre-eleme
by tzot 3y ago
1. I had a similar issue in the fifth grade of elementary school (in my country, elementary school is 6 years with an extra year at age about 5 before pre-elementary school, then three years of middle high, then three years of optional high school before university, but almost everyone does the full 12/13 years.), when we discussed Fahrenheit (foreign) vs Celsius (domestic). The teacher said that 50°C is 106°F because 212°F is 100°C and 212/2 = 106. At the time I said “this doesn't feel right, 106 is not in the middle between 32 and 212” but I couldn't phrase it mathematically yet, and the teacher didn't take my objection in a good manner. Afterwards I learnt that he understood his error but never said a word to me about it.
2. I don't see the colours on the “back sides” of the cards. I just see the cards flipped/rotated 180° around the Y-axis (probably through CSS), so all numbers are visible, just in cards 3 & 4 the numbers are mirrored.
- eviks 3y agoHow did you learn it about the teacher?
- tzot 3y agoFrom his nephew, one year older than me, in the sixth grade with whom we played football (soccer). He said that he heard his uncle talking to his mom.
- mlajtos 3y ago2. Firefox user, right? It should be fixed now. Thank you for reporting this issue. 1. You reminded me of another nice example of wrong shortcuts. Average speed of car from city A to city B is 120km/h. Average speed back (B -> A) was 80km/h. What was the average speed of the car on the whole path (A -> B -> A)? It's not 100km/h.
- firstlink 3y ago> It's not 100km/h. Of course it is... if you're averaging over distance. There's no reason that's less valid than whichever average you have in mind.
- joebiden2 3y agoHow do you arrive at 100km/h if you're averaging over distance? I don't doubt you're right, but I don't see it. My calculation is as follows: suppose the distance between both cities is 120km. The trip A -> B thus takes exactly one hour. The trip B -> A takes 1.5 hours (120km / 80km/h) = 1.5h. The total trip therefore takes 2.5h, the total distance is 240km, which averages at 96km/h (240/(1 + 1.5)). A simple (V1 + V2)/2 is surely possible, but I don't see the value of that average, I can't think of a situation where it would be useful.
- mlajtos 3y agoYou are right. Harmonic mean is the right tool.
- tkot 3y agoI think you are thinking about a case where someone goes 120km/h for 1 hour and then 80km/h for 1 hour instead of going over a fixed distance at 120km/h and then going over the same distance at 80km/h.
- youainti 3y agoTo be pedantic, 100km/h is the arithmetic mean. Of course this is the wrong tool to use (which is your point) but 100km/h is the correct answer if by mean you intend to say arithmetic mean.