A lottery sells 10,000 tickets and awards 10 prizes. If you buy one ticket, what is the probability that you do not win a prize?
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A999/1000
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B9/10
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C9999/10000
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D1/1000
Answer
Correct Answer: 999/1000
Explanation
Introduction / Context:In a finite uniform lottery, the probability of winning equals the number of prize tickets divided by total tickets. The probability of not winning is the complement.
Given Data / Assumptions:
- Total tickets = 10,000.
- Prizes = 10.
- One ticket purchased; each ticket is equally likely to be drawn as a prize.
Concept / Approach:P(no prize) = 1 − P(prize) = 1 − (prize tickets / total tickets).
Step-by-Step Solution:P(prize) = 10 / 10000 = 1 / 1000.Therefore, P(no prize) = 1 − 1/1000 = 999/1000.
Verification / Alternative check:Non-prize tickets = 10000 − 10 = 9990. For one ticket chosen uniformly, P(no prize) = 9990/10000 = 999/1000 after simplification.
Why Other Options Are Wrong:9999/10000 would correspond to 1 prize; 9/10 ignores the precise counts; 1/1000 is P(win), not P(no win).
Common Pitfalls:Mixing up the probability of winning with not winning; not simplifying to lowest terms.
Final Answer:999/1000