Sets vs. Ordered Sets

[MatthewT69]

I was always taught to "NOT ASSUME ANYTHING" in the GMAT unless it's given to you.

Naturally I was caught off-guard by a question that asked about the range of a theoretical set of numbers (A, B, C, D)

The question said nothing about it being an ordered set so I assumed that the range could not be determined since A, B, D, C could stand for any number (104, 92, -236, 14 for example)

Got it wrong. The explanation clearly specifies that it should be treated as an order set.

Is it safe to assume that if a "Set" is provided in a GMAT question, that it's an ordered set?

[RonPurewal]

no, a 'set' does not have to be in order.

this must have come from a non-official source. wherever you got it, the source is in error.

[RonPurewal]

2/
the way mathematicians define the word 'set' is this:
... it doesn't have to be in order,
... repeated values are NOT allowed.

because of this latter restriction—which is very unlikely to be known to non-mathematicians, and, on top of that, just annoying in general—GMAC tends to avoid the word 'set' altogether in these circumstances. instead, GMAC problems overwhelmingly contain the word 'list'.

this avoids all of the problems mentioned here:
• a 'list' doesn't have to be in order,
• repeated values in a 'list' are perfectly okay.
in other words, a 'list' can contain pretty much anything at all, in any order.

[RonPurewal]

...and this is the wrong folder for your query anyway. (this folder is strictly for problems from the FREE GMAT PREP software distributed by GMAC.)

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