Suppose it can be made from the given tiles, then there will be 15 of them.

This is because there are 60 small squares on the board to be covered, 30

light and 30 dark.

So there must be an even number of one type of tiles and an odd number of

the other.

Now the tile type that is used an even number of times is covering an even

number of light squares and an even number of dark squares.

Also the tile type that is used an odd number of times is covering an odd

number of light squares and an odd number of dark squares (as the two

tile types both have an odd number of light and dark squares in them).

So the tiling covers an odd number of light squares and an odd number of

dark squares, which as the board actualy has an even number of both

is a contradiction. Hence no such tiling exists.

RonL