The official infected number in the fifth wave of Covid in Hong Kong so far is around 1.2 million, out of the total population of 7.5 million. So, 16% of our population have got infected with Omicron, and 84% not yet infected. This means the probability that any particular person in Hong Kong has got infected is 0.16. Let's assume this is the case.
Suppose you have N friends. The question is how likely at least one of your friends is among the 1.2 million. A shortcut to finding the answer is to first consider the complementary question of how likely none of your friends has got infected, and that's simply 0.84N.
The complement of this probability is exactly the probability of having at least one of your friends infected, which is 1 – 0.84N.
So, if you have 10 friends, i.e., N = 10, you have 82.5% chance of having at least one of your friends infected. If you have 20 friends, it's 96.94% chance, and if you have 40 friends, 99.9%. On average, each person has around 150 contacts on her or his phone book, according to Dunbar's number. That means the chance is 1.
April 24, 2022
No comments:
Post a Comment
Note: Only a member of this blog may post a comment.