# Fill the World Map with City Dots Of Radius 40

Put a circle of radius 40 at the location of the world's largest city. Now put one for the next largest city that doesn't touch the circle you already placed. Keep going, making sure no previously placed circle is touched!
Data for 1M cities from citypopulation.de, data for smaller cities from geonames.org
Quiz by scambigol
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Last updated: March 21, 2017
 First submitted March 20, 2017 Times taken 108 Report this quiz Report
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 # City 28 Anadyr 20 Anchorage 23 Apia 25 Busselton 8 Cairo 3 Delhi 35 Edinburgh of the Seven Seas 24 Faaa 1 Guangzhou
 # City 15 Guayaquil 31 Hanga Roa 13 Harbin 18 Honolulu 2 Jakarta 11 Johannesburg 7 Lagos 19 Las Palmas de Gran Canaria 10 London
 # City 32 Longyearbyen 33 McMurdo Station 4 Mexico City 16 Mogadishu 9 Moscow 5 New York 17 Novosibirsk 27 Nuuk 29 Port Mathurin
 # City 21 Port Moresby 36 Port-aux-Francais 22 Puerto Montt 12 San Francisco 6 São Paulo 14 Sydney 30 Tiksi 34 Wotje 26 Yellowknife
+1
Level 43
Mar 20, 2017
Wonderful and challenging quiz, as always!
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Level 74
Mar 20, 2017
Fun quiz as always, but I'm not sure these are really circles on this map! A circle projected onto a globe will take different shapes when drawn onto a map, depending on how far north or south you go. A circle will look like a circle at the equator, but as you move further north or south it will become a flatter and flatter ellipse (appearing to become wider and wider), until you reach a circle centred on either pole which will appear as a rectangle going from the left edge to the right edge of the map. Which brings me to my final question: Since they're not circles, what does "radius 40 " refer to?
+1
Level 72
Mar 21, 2017
thanks for all your comments! these are circles just on the map, with radius 40 pixels. i would have liked to place 'circles' of 200 km or so but I'm not sure I would have managed to calculated what the corresponding ellipse would look like, so I simplified calculations by just considering 'circles by n. of pixels'
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Level 74
Mar 20, 2017
Perth is much larger than Busselton, and Narvik is much larger than Longyearbyen, and the circle covering "McMurdo Station" also covers the southern third of the South Island, whose largest city is Dunedin, pop 118,500. Am I getting the instructions wrong here? I thought you have to choose the largest city that is inside each circle.
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Level 72
Mar 21, 2017
you don't have to choose the largest city that is inside each circle. you start with guangzhou and put a circle around it. now you choose the largest city whose circle wouldn't touch guangzhou's circle etc. Perth's circle would touch (only just) the Sydney one so it's ruled out. McMurdo's circle is actually drawn further up than it should since McMurdo is off the map
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Level 74
Mar 20, 2017
One other thing: when you click on the map to enlarge a specific region, the circle covers a different area. You might need to disable the zoom function to avoid confusion?
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Level 72
Mar 21, 2017
I thought about doing that but then also thought that zooming in helps you pinpoint the location of the city you are looking for
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Level 74
Mar 20, 2017
citypopulation.de measures greater urban areas, so working by that principle, Papeete (pop 127,000) is much bigger than Faa'a, which is one of Papeete's suburbs. Papeete city is divided into several communes, one of which is also called Papeete (the downtown commune?) with 26,000, slightly smaller than Faa'a with 30,000.
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Level 72
Mar 21, 2017
you are right, however I only used citypopulation data for cities with 1M inhabitants or more - data of geonames.org is different and making them uniform is a task I don't want to face! I did add Papeete as a type-in, thanks for pointing that out