Looking at integer values only, the area of the internal square would be a multiple of 25 (say 25n) and therefore a side of that square would be a multiple of 5.

The complete square would be a multiple of 25 (say 25n) plus a multiple of 39 (say 39n) for a total of 64n and the side would be a multiple of eight. The difference would then be a multiple of 3. The width of the wooden strip would be half that, or 1.5 inches.

However, if you are allowed to use fractions any of the values would work. You would simply need to have the sides of the inner square be 5/8 of the side of the outer square.

Tani Wolff - Kaplan wrote:Looking at integer values only, the area of the internal square would be a multiple of 25 (say 25n) and therefore a side of that square would be a multiple of 5.

The complete square would be a multiple of 25 (say 25n) plus a multiple of 39 (say 39n) for a total of 64n and the side would be a multiple of eight. The difference would then be a multiple of 3. The width of the wooden strip would be half that, or 1.5 inches.

However, if you are allowed to use fractions any of the values would work. You would simply need to have the sides of the inner square be 5/8 of the side of the outer square.

Great Work,