BlindVision wrote:Hi Stuart, very good explanation! I was wondering, how would we know to find the average between the spaces if the Statements do not tell us that the booths are evenly spaced? What if the 1st 3 cones were 6m apart [spaced] from eachother = 12m, and the 4th cone were 13m from the 3rd cone? Thus, making one to believe the answer is "E". Are there certain assumptions that should be applied to DS problems such as this one? Thank you, Stuart.
P.S. I enjoy reading your posts, they are very clear and easy to understand, and enlightening!
Hi!
We don't know that the booths are evenly spaced and we're not assuming that they are. It's very dangerous to make any assumptions at all in data sufficiency and you should definitely avoid doing so!
The reason that we take the average is because we know that at least one member of every set will be at or below the average (after all, if every member of a set were above the average, then it couldn't very well be the average, could it?).
This questions asks us if at least one of the distances between booths is less than 10. Since the average is 8.33, we know for sure (i.e. we can answer a definite "yes" to the question) that at least one of the distances is less than or equal to 8.33.
That said, there are still an infinite number of possibilites for exactly how far apart the booths are - but we've answered the question posed.
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