Every week we feature an original logic puzzle for your brain-bending pleasure. They follow a format similar to those on the LSAT, and their difficulty ranges the full gamut. Good luck!

Written by: Alexander JL Theoharis

Derek, Eli, Forest, Gary, Henry, Ivan, and Jesse are knights sitting around a square table. Each side of the square holds one person, and each corner holds one person. There is one empty seat, since the King recently passed away.

1. Forest and Eli are not seated on a corner.
2. Forest and Jesse are seated next to Ivan.
3. Jesse is seated to the left of the empty seat, as he was the King’s left-hand man.
4. Eli is seated across from Jesse, so they can keep an eye on each other.
5. Gary and Derek are brothers and are always seated next to each other.

1. Who is seated to the right of Eli?

a. Henry

b. Gary

c. Forest

d. Derek

e. Ivan

2. For the purposes of this question, assume the empty seat is next to Derek. Who is seated to Eli’s left?

a. Henry

b. Gary

c. Forest

d. Derek

e. No one.

3. If Eli and Jesse become on better terms and Rule 4 is removed, who is seated to the right of the empty seat?

a. Eli

b. Gary

c. Derek

d. Gary or Derek

e. Gary, Derek, or Eli

Answers after the break.

Answer Key and Explanation

First we should acknowledge how the table is set up. We know that there’s eight spots around the table, and one of them, the King’s seat, is empty. We also know that half the people will be seated on corners, and the other half seated on the sides of this square table.

Building up a model based on the above rules should be relatively simple:

1. We know that F and E need to be seated on a side, not the corner of the table.

2. Forest and Jesse flank Ivan on either side.

3. The seat to the right of Jesse is empty (the King’s seat).

4. Eli needs to be seated across from Jesse. If this doesn’t work out in your diagram, try shifting Forest and Eli’s starting positions and getting to this step again.

5. We can’t be certain where each of them are sitting, but since there’s only one open slot left, we know that they need to go in the place that has two open spaces next to each other.

Question 1:

Your diagram should look like this:

By process of elimination we can work out who CAN’T be seated in the seat to the right of Eli: namely, everyone who we currently have a place for. The only one left is Henry, answer a.

Question 2:

Same layout, but now we know which order the two brothers are in, since we can place Derek definitively to the King’s right. That forced Gary to be next to Eli, so the answer is b.

Question 3:

This prevents Eli from being locked into the position across from Jesse. Thanks to this, Eli can now move to be across from Forest, the only other possible position for him (you can try other places, but they violate additional rules). This gives us this diagram:

Which means that in addition to our old two options (Gary and Derek, either of whom could have been seated next to the King) we now can add Eli. The correct answer is e.