I have a tough, tough real world probability problem

My mom had an extremely rare disease. 1 in 15 million get it per year. I have somehow met 3 others. I am 44 and have met 1000 people total. There are 400 million people in this place total steady population.

What are the odds of me and of ANY human meeting 4 people with the disease.

To calculate the odds of meeting four people with the disease, we can use the concept of probability. The probability of meeting someone with the disease can be calculated by dividing the number of people with the disease by the total population. In this case, the probability of meeting someone with the disease is 1 in 15 million.

Now, to calculate the odds of meeting four people with the disease, we need to multiply the probabilities together. Assuming that the probability of meeting someone with the disease remains constant throughout your interactions, the probability of meeting four people with the disease would be:

(1/15,000,000)^4

This probability is extremely low, indicating that it is highly unlikely for you or any individual to meet four people with such a rare disease, given the population size and the rarity of the condition.

• So the number of people I know doesn't matter? Oh yah. Ok, if we localize it, just use the population? like (1/200,000)^4 in the area?

• No wait. Not that.

• Here is my reddit answer: level 2 Aerospider · 5 hr. ago On meeting a person there is an 880 / 300M chance they have the disease. The formula for this occurring exactly 4 times out of 1000 is (880/300M)4 * ((300M-880)/300M)996 * 1000!/(4!996!) So yes, incredibly low. But do note that this is discounting meeting exactly 0, 1, 2, 3, 5, 6, 7, 8, etc.

• How do you crack 1000!/(4!996!), you know Dr. Ali?

• Sorry Dr Ali. Way off. This is a 4 variable. You need to include my circle against other possibilities. AND total population. Think about how to add that.

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