Episode 1 - Napkin Math

But what if, you are a math nerd?

Will you hate us for fast forwarding through all the math?!

Well then, take a moment and napkin math with me!

The things we need to know, and in case you forgot, the question is “how many murderers might you walk past in your life?”, include the following:

• How many people does the average person “walk past” in your life? And what counts as walking past, for that matter!

• How many murderers are there?

• How long does the average person live?

So now, to attempt to answer those questions!

How many people does the average person walk past each day?

Obviously, people can live in vastly different environments. There are hermits and there are bus drivers in Dhaka. But how many people might the average person walk by? Using a bell curve distribution (and very little else) we supposed that 20% of the population would be in the “very few walks by each day” category, 20% of the population would be in the “tons of walks by each day” category, and the rest of the population would be in the “average walks by each day” category. We estimated these to be 5 new people a day, 100 new people a day, and 15 new people a day respectively. This indicated to us that most people walk past an average of 30 new people each day.

How many murderers are there?

There is a lot of interesting data here that I researched and played around with - likely worthy of a whole separate blog post at some point - but to keep things short and sample here, let’s stick with what ended up mattering: the murder rate. In 2018 (which was the last published data I could find for some reason) the murder rate in the US was 5 in 100,000 or 0.005% of the population. If the murder rate is similar this year, then that means there would be around 16,475 murders, and as such murderers, each year. As a side note, it turned out that things like serial killers didn’t change this number much but again, probably a topic for another day. We also assumed, for the sake of simplicity, that you could * technically * walk past any of these people before they were incarcerated.

How long does the average person live?

Probably the easiest question we had to answer - the average life expectancy in the US is 78.5 years.

So what’s the answer already?!

So if we take the 28,652 days most people live, and the 30 new people each day that gives us 859,360 new people to walk past in a lifetime. And based on the murder rate of 0.005% we get 42.

Forty two murderers the average person could walk past in their lives.

Hide your kids, hide your wives!