Powerball Jackpot

Hello, I need help with my homework! I'm not really good at probability but I really want to learn, if its possible to help me with the answer and how to get to the answer will be great!

2. Assume that each week, on average, 50 million lottery tickets are sold. What are the chances in any single week that someone wins the jackpot?
3. On average, how often will there be a winner?
4. Now, let’s say I have a time machine and I randomly send you hundreds of years into the future. Because of the vagaries of interdimensional quantum mechanics the machine is unable to tell you ‘when’ it is, however, it does keep track of each powerball jackpot that was won during its most recent trip. You immediately ask the first person you see what year it is and she responds, “It is year 342 since our merciful overlord Ultron first ascended to the throne.” This sets off several alarm bells in your head, but doesn’t help at all in determining ‘when’ you are. You think for a moment and you suddenly remember Dr. Smith probability class. After mouthing a quick thank you to your wise and benevolent professor (who is now long dead) you ask, “Do you still have the powerball lottery?” This future woman looks at you like you’re insane and then says, “Of course, the jackpot is up to $500 trillion this week.” You sprint back to your time machine and see that the powerball jackpot counter is at 2759. How far into the future did you go?
5. What could mess up this estimation of the date?