Answer:
0.3125
Step-by-step explanation:
Use definition of geometric probability:
[tex]P=\dfrac{\text{Desired Length}}{\text{Total Length}}[/tex]
In your case,
Total Length = 8 miles
Desired Length = 7 - 4.5 = 2.5 miles,
so the probability is
[tex]P=\dfrac{2.5}{8}=\dfrac{25}{80}=\dfrac{5}{16}=0.3125[/tex]