I think it’s probably something like 10,000 - 10,000 hairs on your head.)
- Okay so 10,000.Let’s call it 10,000.So what are the chances of two people in London having the same number of hairs on their head? Brady’s gut reaction was very close to zero, but let’s say to be fair we are not counting bald people, and assume everyone has roughly 10,000 hairs on their head. We can use Fermi estimation to solve this question and estimate the chances of two people having the same number of hairs on their head is very unlikely. So let’s apply the same principle to our Londoners and their hairs.If we have 8 million people and we have 100,000 hairs that’s 8 billion hairs.So clearly some people are sharing hairs.So let’s be generous and say 150,000 hairs per person, that’s still 12 billion hairs.So I think we’ve got a pretty good answer. Common sense and the pigeonhole principle are surprisingly useful and applicable in many different situations. For example, if there are more people than options, then some people will have to double up. This is also true of passwords or birthdays - if there are only a certain number of options, then two people will have to pick the same one.
Studying maths can help with this type of estimation, but people who do a lot of it in their day to day lives are often better at it. To help with this, MEL Science has created the How to Never Lose subscription box which includes a bean machine, normal distributions and other probability games. Plus, you can get 50% off your first purchase with MEL Science - check out the link in the video description or visit melscience.com to find out more. It is 100% likely that two people in London will have the same number of hairs on their head, due to the Pigeonhole Principle.