Wikipedia:Reference desk/Archives/Miscellaneous/2020 October 5

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October 5

face masks for covid19, 3% effectiveness meme

A person named Paul says his coworker told him that face masks are only 3% effective. Paul believes the claim. Paul doesn’t know what the 3% “is of”(in fact doesn’t recognize the issue since he’s not very science oriented). So my questions are: is the 3% meme out there somewhere on social media or talk shows or websites, and what is it 3% of? (Like does it mean a mask reduces infectivity rate by 3% compared to the of infection without a mask near a contagious person?(If so, they could conceivablymean the rate of infection per person met drops from 3.1% to 0.1%, but probably that’s not what they meant). I haven’t see it on Google.Rich (talk) 03:07, 5 October 2020 (UTC)

Our article on the topic is Face masks during the COVID-19 pandemic with 394 references, so there's plenty to read there. Graeme Bartlett (talk) 05:56, 5 October 2020 (UTC)

In New York the daily new infection rate dropped by 3% per day after a policy requiring that people wear face masks or coverings in public took effect.^[1] We do not know what percentage of people followed that rule, but apparently such policies have an effect. The problem is that too many people only think about their personal safety or that of their loved ones. If we collectively bring the effective reproduction number down to well below 1, say to 0.8, the pandemic will be over in a jiffy – every day the number of new cases will be lower by about 3%, which is a reduction by a factor of 10 every 10 weeks. So within a couple of weeks mini outbreaks can be handled comfortably by contact tracing and isolation (quarantining), and if everyone remains reasonably cautious life (work, school, recreation) can largely return to normal. Every measure adds a bit to bringing the effective reproduction number down – frequent hand washing, social distancing, and wearing suitable face coverings. If everyone had acted socially responsibly, the pandemic would have been over months ago.  --Lambiam 06:45, 5 October 2020 (UTC)

Dice with all same-length edges and same side count at all corners

I don't know the proper terminology, so I will try to explain it with what I do know, math. A standard 6-sided die has 6 square sides. They are squares. All edges around the side are the same length. All corners, where the edges meet, have the same number of edges. That is three per corner on a standard 6-sided die. If you use equilateral trianges for sides, there are two options that I know of. You can have a 4-sided die. All edges are the same length. Each corder has three edges coming from it. You could also have 20 sides. All edges are the same length. All corners have 5 edges coming from them. If all of that makes sense, my question is what to call this type of die. I've seen many dice that have edges that aren't all the exact same length or some corders with five edges and some with four edges on the same die. They may be "fair" dice, but that isn't what I want to focus on. I am only concerned with dice where all edges are the exact same length and all corners have the same number of edges. Then, I want to know if triangles and squares are all we can use. Is it possible to make a die like that using a pentagon or hexagon? Truangles are weird because I know you can do 4 sides and 20 sides. I assume there are many more sides you can do. I saw a 60-sided one, but the sides weren't really triangles. One side had a end in it. It also looked like some corners had six edges and some had five. I saw a 120-sided die, but the triangles were not equilateral. The overall topic is map projections. I'm reading about various map projections and that leads to projecting a globe onto a die and unfolding the die to create a flat map. 97.82.165.112 (talk) 18:20, 5 October 2020 (UTC)

Does Platonic solid answer your question?--Shantavira|^{feed me} 18:30, 5 October 2020 (UTC)

Yes. Thanks. I knew it had to have a name. 97.82.165.112 (talk) 18:40, 5 October 2020 (UTC)

The topic of the question is well within the purview of the mathematics section of the Reference Desk.  --Lambiam 09:36, 6 October 2020 (UTC)

If all edges of equal length and all vertices spawning the same number of edges are the sole criteria, then Archimedean solids also qualify. Those have non-identical polygonal faces, but that is not a criterion you have specified as mandatory. --Cookatoo.ergo.ZooM (talk) 16:28, 7 October 2020 (UTC)

OP is evidently interested in dice, and Archimedeans are not fair dice, though their duals are. (And these are not all the fair dice.) —Tamfang (talk) 01:33, 9 October 2020 (UTC)