Six different dice with their top faces erased have been given. The opposite faces of each dice have numbers which add to 13. All dice have the numbers from amongst 4, 5, 6, 7, 8 and 9 printed on them.
If the odd-numbered dice have even numbers at their bottom faces, what is the sum of those even numbers ?
The odd numbered dice are 1st, 3rd and 5th. Consider this deduction.
- Dice No. A: Face opposite 6 is 7 because 6 + 7 = 13. Similarly, face opposite 4 is 9. So, the numbers that appear on the sides are 4, 6, 7 and 9. Out of the remaining 5 and 8, the bottom face is 8.
- Dice C: Similarly, 8 is at the bottom.
- Dice E: 4 is at the bottom.
So sum is 8 + 8 + 4 = 20.