Logical ReasoningDifficulty: Hard

PT112 S3 Q21 Explanation

Sandy: I play the Bigbucks

A free, expert breakdown of this official LSAT Logical Reasoning question.

TopicsFlaw

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Stimulus

Sandy: I play the Bigbucks lottery—that’s the one where you pick five numbers and all the players who have picked the five numbers drawn at the end of the week share the money pot. But it’s best to play only after there have been a pot increases each week that there is no winner.

Alex: No, you’re more likely to win the lottery when the money pot is small, because that’s when people are playing.

What this question is testing

Flaw

Your task

Describe the reasoning error the argument actually commits.

Common trap

Answers that name a real logical flaw the argument doesn't actually make.

Winning move

Articulate the gap in the reasoning yourself, then match it to the choice that describes that gap.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
21.

Which one of the following most accurately describes a mistake in the reasoning of one of

Answer choices

  1. Not True2% picked this

    Sandy holds that the chances of anyone’s winning are unaffected by the number of times

    Sandy doesn't make any comments about how playing multiple times does / doesn't affect your odds of winning. She's only talking about when it's worth playing, not how many times someone plays. Everyone's common sense knows that the more you play, the more chances you have to win, so for someone to hold that your chances of winning are unaffected by how many times you play would have a really crazy sense of probability.

  2. Correct65% picked this

    Alex holds that the chances of Sandy’s winning are affected by the number of

    Why this is right

    This is certainly a true description of Alex's argument. His holding is the conclusion "you're more likely to win", which is about the chances of Sandy's winning. His evidence is about how many people are playing when the pot is large vs. small. If we didn't diagnose why this was flawed, we might guess this answer simply because it's at least an accurate description. As discussed above, this is flawed thinking because your odds of winning Bigbucks are based purely on the math of how many possible ways there are to pick five numbers. If there are ten options for each number (0 - 9), then there are 100,000 ways to pick five numbers, and thus the odds of any five number ticket winning are 1 out of 100,000, regardless of how many people play.

    Skill tested: Flaw · how this choice captures the argument's function is the move to repeat next time.

  3. Bad Conclusion Match12% picked this

    Sandy holds that the chances of anyone’s winning are unaffected by the size

    Sandy never talks about the chances of anyone winning. Her conclusion is about when it's optimal to play based on the size of the pot. She isn't ever claiming that your chances of winning change. She's implying that the potential payout of winning is bigger in some cases than others.

  4. Opposite4% picked this

    Alex holds that the chances of Sandy’s winning in a given week are unaffected by whether anyone has

    Actually, because of Alex's flawed belief that the number of people playing affects one's chances of winning, he would actually think that your chances of winning are affected by whether someone won the week before. He would think, "If someone won last week, then this week's money pot is very small, so the fewest number of people will be playing, which makes you more likely to win."

  5. Bad Conclusion Match17% picked this

    Sandy holds that the chances of there being a winner go up if no one has won the

    Sandy never talks about the chances of anyone winning. Her conclusion is about when it's optimal to play based on the size of the pot. She isn't ever claiming that your chances of winning change. She's implying that the potential payout of winning is bigger in some cases than others.

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