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Dave S.

asked • 05/26/18

Probability of winning raffle with multiple tickets (max one win each)

I have 90 tickets in a raffle.
20,000 people have bought tickets.
Each person has bought between between 60 and 100 tickets.
The total number of tickets sold is 1,360,000 giving an average of 68 tickets per person.
There are 5,000 prizes.
Each person can only win once, so their tickets are removed from the raffle as soon as they win a prize.

What are my chances of winning a prize given I have 90 tickets.
(The exact distribution of the ticket allocation is not known, so an assumption that everyone else but me has 68 tickets would be a close enough estimation)?

1 Expert Answer

By:

Andy C. answered • 05/27/18

Tutor
4.9 (27)

Math/Physics Tutor

Dave S.

Thanks Andy,
Seems logical although a 38.6% probability seems a little higher than i though the answer would be I was expecting closer to 33%.
If I replace the 90 tickets with 68 tickets so I now have the same tickets as everyone else the equation you have provided gives me a probability of 29.2%, but my logic tells me that with 20,000 people and 5,000 different winners all with the same odds of winning the probability of anyone including me should be 25%
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05/27/18

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