Q14

[xiahong0]

Hey Brian,

I pretty much have the exact same model and got every question right except number 14. What I'm having trouble with is perhaps the wording of the problem. The correct answer is C, but I can't understand why it isn't possible for F to be in the third slot. Yes, it's true that the third slot has to be 10, and the only 10, but why can't F be there? I don't see anywhere that states that F can't have discovered stuff in both the 9th and 10th centuries, so it seems possible that F could be in the third slot. This also seems plausible to me since it doesn't say anywhere that all three archaeologists must be used. For example, question 17's right answer is D (4). That would imply that we'd have 4 Fs and only one slot left for either G or O. I'm really confused on this one. Any help would be appreciated.

[bbirdwell]

You've forgotten one of the constraints!!
"Exactly one site by G, and it's from the 10th."

The question says "exactly one site is from the 10th century." Sp that one has to be G.

[sarahcferrara]

Hi birdwell,

I had trouble wrapping my brain around the wording of this question. Is it essentially adding another constraint? Is it now saying that there is only one 10th century site out of five sites? Is that why F can't be the 3rd site because it has to be G?

thanks,
Sarah

[yvetterc23]

Your right it is adding a contraint. For this question there is only one site that's 10th century. Three HAS TO BE 10, be a more recent site than 4. Since G has one site and its from the 10th century, that removes F.

So yes to your question. Hope this helped.

[rinagoldfield]

yvetterc23, I think you answered Sarah's question perfectly.

To backtrack a bit: we know the fourth site must be visited in the 9th century because it's not discovered by O (so, no 8) and it has to be older than the third site (so, no 10).

If the fourth site is 9, then the third site has to be 10. This is because third site must be newer than the fourth.

So, in general, the third site is 10. This question tells us that ONLY the third site is 10. Therefore, this site must have been discovered by G.

--Rina