Question

King Edvard gives Anna the layout of a cubical chamber marked with the EXIT door (Figure 1). Anna’s view in the chamber looks like Figure 2, which has only one correct EXIT door. If both the figures are cube nets that fold upwards, which one is the correct EXIT door in Figure 2?

• A. Face D
  
• B. Face B
  
• C. Face A
• D. Face C
  

Answer 1

The correct option is A Face D


The EXIT door is clearly in one of the four red faces marked A, B, C and D in Figure 2.

Note that both the cube nets fold upwards. If Anna stands on the blue face which is currently seen as the floor of the chamber as per Anna's view in Figure 2, upon folding upward, we observe that

(1) the green face will be the wall in front of her,
(2) the red face B will be the the wall to the left of her,
(3) the red face C will be the wall to the right of her,
(4) the red face D will be the wall to the backside of her, and
(5) the red face A will be the ceiling of the chamber.

If we fold the net given in Figure 1 upwards in the same way, and complete the cube by keeping the blue face as the floor, then we observe that Anna has to face towards the green face (wall) in the folded Figure 1. Then, the face marked with the EXIT door will become the wall on the backside of her.

From (4), we deduce that the EXIT door must be in Face D.

Option d is, thus, the correct answer.