What are the odds that two different people will send you a text with an obscure symbol, a week apart?

Question

Assume that these events take place in the United States among native English speakers.

What are the chances that someone would send you a text message containing the inverted question mark (used in Spanish), and then, a week later, a completely different person sends you a text message containing the inverted question mark?

Do the odds increase, decrease, or stay the same depending on how much time has passed between the two events?

Answer 1

Hi Roseanne F.,

An interesting question, Thank You ¡

There are so many inputs to the probability, I hardly know where to start. Basically, you must consider whether there are any causes which might make the sending of the symbol a non-random event. If there aren't, then it's random, with constant odds (but see below!).

Let's call the first circumstance (two occurrences seven calendar days apart) result A, and the second circumstance (two occurrences fourteen days apart, let's say) result B.

One thing you need to know is, has the pool of "contacts", i.e. people who could send you texts, changed over time? If it is continually increasing, then the probability of getting texts, including with the symbol, will likely increase over time, other things being equal.

These days, you'd question if the particular event might be related to a message with a virus, which is being spread inadvertently among your contacts, or perhaps just to a particular message which is "going viral". That's non-random, and requires special calculations. These things are inherently unpredictable in advance, though it is predictable that continually more malicious programmers out there are trying to attack your devices! Use anti-virus software, and be cautious!

How about this possibility: your contact list is becoming more international in scope, and therefore you are getting more frequent preguntas. Posible¿

If you wanted to delve more deeply into the odds, you'd need to analyse just why a native English speaker would include a particular symbol in a text. The reason (and the accompanying odds for each person) might differ from person to person; that wouldn't directly affect how you answer this question, but it would suggest that the overall reason set among your contacts might be drifting over time, and that could affect the odds of B vs. A, because there would likely be a trend to the overall receipts of such text messages.

One further note: the question is asked casually, as if perhaps the event B "time gate" is open. That's not really fair, b/c over infinite time, you'd expect to get infinite sends of the symbol!

Now here's a little tidbit on probability for you to mull over. Also in Spanish, the letter "ll" is used, with sound like the "y" in "yellow". In the Andes, there are 61 named mountains with a single occurrence of "ll" in their name, with summits of 4000m or higher. How many mountains would you predict with 2 occurrences of "ll" in the name, and how many with 3 occurrences of "ll" in the name? The answer (https://en.wikipedia.org/wiki/List_of_mountains_in_the_Andes ) is likely to surprise you!

-- Cheers, -- Mr. d.