An ordinary die, on which the dots on opposite faces add up to 7, is shown below. What is the total number of dots on the three faces that cannot be seen?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 9
On an ordinary die the dots on opposite faces add up to 7. The three hidden faces (bottom, back and left) are opposite the three faces that can be seen.
Bottom face, opposite the top 4: \(7-4=3\)
Back face, opposite the front 6: \(7-6=1\)
Left face, opposite the right 2: \(7-2=5\)
Total of the hidden faces: \(3+1+5=9\)
Why the other options are incorrect
Option (1) 21 — Incorrect. This is the total of all six faces, seen and hidden.
Option (2) 8 — Incorrect. This leaves out the hidden face at the back, opposite the 6 in front.
Option (4) 4 — Incorrect. This leaves out the hidden face on the left, opposite the 2 on the right.