I read the following in a problem statement in {1}:

You go to a party with 500 guests.

Has the party 500 or 501 guests in total? Or is it ambiguous?

{1} Bertsekas, Dimitri P., and John N. Tsitsiklis. Introduction to probability. Vol. 1. Belmont, MA: Athena Scientific, 2002. Harvard

  • 2
    It's ambiguous. But this is hair-splitting logic, not really related to learning or using English. Commented Oct 19, 2016 at 16:40
  • @FumbleFingers Some languages may not have such PP-attachment ambiguities. Commented Oct 19, 2016 at 16:46
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    And some languages may not support the other ambiguity regarding whether with attaches to the verb go or the noun party (where in the former case, there might already be thousands of guests at the party). That might be a meaningful thing to ask about, but frankly I don't think the difference between pre-increment and post-increment is a meaningful aspect of "natural" languages - it's just a computer thing. Commented Oct 19, 2016 at 16:57
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    I agree that it's ambiguous. Given that this is a probability textbook, I'm going to guess that the total number is supposed to be 500, because *n*/500 is a lot easier to grasp than *n*/501.
    – stangdon
    Commented Oct 19, 2016 at 17:21
  • Does the party have 500 or 501 guests? Answer: It depends on whether you count yourself as a guest.
    – Lambie
    Commented Oct 19, 2016 at 18:18

2 Answers 2


It's ambiguous, but we can make a guess as to the meaning. It depends on how you interpret with.

  1. I'm going to a party. (What kind of party?) A party with 500 guests.

In this interpretation, "with 500 guests" refers to how many people will be at the party. This number presumably includes the speaker.

Because the source is a probability textbook, I would say that this is the likely interpretation. Hypothetical scenarios in probability usually prefer round numbers.

  1. I'm going, with 500 guests, to a party.

In this interpretation, you are going along with 500 other people, for a total 501 guests. This interpretation implies that you are the one bringing these guests. There may even be more people at the party, if there are others who brought guests as well.

If the number were smaller than 500 (say, 3 or 4), and if the quote were from a real person rather than a textbook, this is the interpretation I would tend to go with.

  • The question title specifically focuses on the issue of whether the number of people at the party is 500 or 501 (i.e. - does the number include the speaker?). So it's not asking about the other potential ambiguity (is 500 the number of people who specifically went with me, or the total number of people at the party?). Commented Oct 19, 2016 at 17:11
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    @FumbleFingers I think the ambiguities are closely related. Whether the speaker is included depends on whether the number refers to those at the party or those that the speaker brought. I've edited my answer to note this.
    – cbh
    Commented Oct 19, 2016 at 17:34

The meaning of the statement hinges on the meaning of with, and there is also an assumption that you are not crashing the party but are an invited guest.

"a party to which 500 people had been invited" (and you are one the invitees) [ergo 500]

"a party where 500 guests [of an unknown number of invitees] have already shown up" (and you are an invitee) [ergo 501]

Or if you are a party-crasher, 500.

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