Well yes, now the chance of drawing the wining ticket is 1/19. But I think a better analogy would be, say there are 20 tickets in a hat, one of which is a winner. An unknown number (but less than 20) of people may have drawn tickets from the hat already, and one of them might have won already. You don't have any information about that. Nonetheless, what is your chance of winning if you draw one ticket? It is still 5%, based on the knowledge available.
Not clear on this. You may think your odds are 5%, but in fact they are not. If the ticket has been drawn, your odds are 0. If the ticket has not been drawn, your odds are better than 5%, and dependent on the number of tickets still in the hat.
Reminds me of the game show that has door #1, #2, and #3 (Price is Right?). One door has something valuable, the other two do not. After the contestant has picked a door, the MC opens one of the two remaining doors to show that it does not contain the valuable prize. Then the MC asks the contestant if he or she wants to change their choice to the other door, or keep their original choice. What is the right thing to do?
Is sticking with the original choice is the best thing, because that pick is still in the running, and there is only 1 other left? Or maybe it doesn't matter either way as there is a 50/50 chance no matter what you do? Nope, both are wrong. The proper choice is to always switch.
Here's why - the first pick has a 1/3 chance of being correct, but switching gives you the valuable prize 2/3 of the time. So nothing changes the odds of the first pick (1/3), but eliminating one door (the open one) doubles the chance of winning.