Question 15
The beaver has 16 pine trees of four types (
), four of each type. Trees of the same type have the same height, and different types have different heights. The beaver plants the 16 trees in a $4\times4$ garden so that each type appears exactly once in every row and every column. At each position around the garden, the beaver puts a sign showing the number of trees visible in that row or column from that position. Note that shorter trees behind taller trees are hidden. The illustration below gives an example of the numbers on the signs for the planting arrangement shown.
The following picture shows some signs that have been placed around the garden.
Which four trees below could be planted at A, B, C and D, respectively?
), four of each type. Trees of the same type have the same height, and different types have different heights. The beaver plants the 16 trees in a $4\times4$ garden so that each type appears exactly once in every row and every column. At each position around the garden, the beaver puts a sign showing the number of trees visible in that row or column from that position. Note that shorter trees behind taller trees are hidden. The illustration below gives an example of the numbers on the signs for the planting arrangement shown.The following picture shows some signs that have been placed around the garden.
Which four trees below could be planted at A, B, C and D, respectively?
