First, let's find the radius of the pool. The diameter is 18 feet, so the radius is half of that, which is 9 feet.
Now, let's find the area of the pool. The formula for the area of a circle is π * r^2, where π (pi) is approximately 3.14 and r is the radius.
Area of the pool = 3.14 * (9 feet)^2 ≈ 254.34 square feet.
Next, let's find the area of the concrete walkway. Since it's uniform and 4 feet wide, we add 4 feet to the radius of the pool to get the radius of the outer circle (pool + walkway).
Radius of outer circle = 9 feet (pool radius) + 4 feet (walkway width) = 13 feet.
Area of the outer circle = 3.14 * (13 feet)^2 ≈ 530.66 square feet.
The area of the walkway alone is the difference between the area of the outer circle and the area of the pool:
Area of walkway = Area of outer circle - Area of pool
≈ 530.66 square feet - 254.34 square feet ≈ 276.32 square feet.
Now, multiply the area of the walkway by the cost per square foot of concrete:
Cost of concrete = Area of walkway * Cost per square foot
≈ 276.32 square feet * $4.25 per square foot ≈ $1174.70.
So, approximately, it will cost $1174.70 for the concrete.