The path is circular. The distance covered in one lap is the same as the circumference of the circle. The formula for finding the circumference of a circle is
circumference = 2 x pi x r
r = 1/8 = 0.125
pi = 3.14
one lap = 2 x 3.14 x 0.125 = 0.785
The distance covered in running 4 laps = 4 x 0.785 = 3.14 miles