11 I
Reynaldo has a square fish pond in his back yard.
The pond is 2 feet on each side. He would like to
border the pond with 3 in. by 3 in. square tiles,
alternating between squares of yellow and green
tiles, as shown.

See below

Step-by-step explanation:

The question in full is attached

The pond is 2 feet = 2*12 inches = 24 inch each side

Each side is 24/3 = 8 tiles long

The first border line (yellow)  has:

The second line (green) has:

Each following line has 4 more tiles

a) As AP sequence it looks as:

So

b) Considering the alternating colors,

Yellow sequence:

Green sequence:

4sqrt5

step-by-step explanation:

the base has dimensions of 8 x 4, so the diagonal is 64 + 16 square rooted or 4sqrt5.