Answer:
1.25 mi
Explanation:
Think of this in terms of a graph in the x-y axis
Bill starts out at point (0,0)
He walks 1/2 mile south (i.e 0.5 miles in the -y direction) and ends up at (0,-0.5)
Next he walks 3/4 mile (0.75 miles) in the +x direction and ends up at (0.75, -0.5)
Then he continues to walk 1/2 mile (0.5 miles) in south in the -y direction and ends up at (0.75, -1).
His final distance from the starting point (0,0) from his end point (0.75,-1) is simply the distance between the 2 coordinates (see picture for formula).
hence,
D = √ (0.75 -0)² + (-1 - 0)²
D = √ (0.75)² + (-1)²
D = 1.25