What is the smallest number of people in a room to assure that the probability that at least two were born on the same day of the week is at least 40%?
I understand when approaching this type of problem, you simplify it so there's only 365 days. Also, I thought you go about the question by finding the probability that no one is born on the same day of the week. Then you subtract by 1 to get the solution:
Therefore, if the first person can have a birthday on any of 365 days, and the second is (365-8) because 1 week has to be removed (since question asks at least two born on the same day). I thought the answer is:
The solution is 4 people but when I enter r=4, I get 5.6% which is obviously wrong. Any help is appreciated. Thank you.