Final answer:
The maximum possible area of region s can be found by creating a square inside the larger circle and calculating the difference in areas.
Step-by-step explanation:
To find the maximum possible area of region s, we need to consider the arrangement of the circles. The circles with radii 1 and 3 should be placed inside the circles with radii 5 and 7. This creates a square inside the larger circle, with side length equal to the sum of the radii of the smaller circles (1+3=4). The maximum possible area of region s is the difference between the area of the large circle and the area of the square, which is
π(7²) - (4²)
49π - 16
So, the maximum possible area of region s is 49π - 16.