Raffle Strategy: Suppose 100 entries total; you entered 10 times. Then...

sarbee

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Jan 8, 2018
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I've been puzzling over this for a while for some reason, so I'd love to get some feedback on it and hopefully put the matter to rest in my head. So here's the problem: Imagine that you are entering a raffle. You can enter as many times as you want. Numbers are assigned to each entry based on the order in which they are received. A number is then chosen at random to select a winner, and all numbers have an equal chance of being selected. Let's say there are 100 entries total, and you choose to enter 10 times. It seems simple enough; you have a 1 in 10 chance of winning, right? But here's what I've been wondering about: Would it benefit you to purchase 10 raffle tickets in one block or spread out over a period of time? Based on the number of tickets it seems like it shouldn't make a difference, but I can't help but think purchasing the tickets in a block (ie, assigning yourself 10 consecutive numbers, such as 1-10) makes your entry a larger target, therefore increasing your odds? If a number equal to or less than 10 is chosen, you automatically win; it doesn't really matter what number it is. This seems more beneficial than spreading out your entries and hoping one of your numbers is chosen precisely. I guess what I'm getting at is choosing numbers in a block provides something of a margin of error; if you only had the #6 ticket within the 1-10 range, for example, a 5 or a 7 winning number is frustratingly close. Buying out the whole block decreases your odds of the winning number being one off. In the 1-10 example, it could only happen once, if an 11 is selected as the winning number. I don't know, maybe I'm putting too much thought into this, but I'd love to get to the bottom of it! If this strategy does increase your odds, how can you calculate that?
 

Subhotosh Khan

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Joined
Jun 18, 2007
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18,249
I've been puzzling over this for a while for some reason, so I'd love to get some feedback on it and hopefully put the matter to rest in my head. So here's the problem: Imagine that you are entering a raffle. You can enter as many times as you want. Numbers are assigned to each entry based on the order in which they are received. A number is then chosen at random to select a winner, and all numbers have an equal chance of being selected. Let's say there are 100 entries total, and you choose to enter 10 times. It seems simple enough; you have a 1 in 10 chance of winning, right? But here's what I've been wondering about: Would it benefit you to purchase 10 raffle tickets in one block or spread out over a period of time? Based on the number of tickets it seems like it shouldn't make a difference, but I can't help but think purchasing the tickets in a block (ie, assigning yourself 10 consecutive numbers, such as 1-10) makes your entry a larger target, therefore increasing your odds? If a number equal to or less than 10 is chosen, you automatically win; it doesn't really matter what number it is. This seems more beneficial than spreading out your entries and hoping one of your numbers is chosen precisely. I guess what I'm getting at is choosing numbers in a block provides something of a margin of error; if you only had the #6 ticket within the 1-10 range, for example, a 5 or a 7 winning number is frustratingly close. Buying out the whole block decreases your odds of the winning number being one off. In the 1-10 example, it could only happen once, if an 11 is selected as the winning number. I don't know, maybe I'm putting too much thought into this, but I'd love to get to the bottom of it! If this strategy does increase your odds, how can you calculate that?
If you assume the drawing process to be truly random - then grouping or not grouping will not make a difference.
 
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