Convert 5 500 to miles​

Ineed i do not understand i'm only 8

The physical fitness of an athlete is often measured by how much oxygen the athlete takes in (which is recorded in milliliters per kilogram, ml/kg). the mean maximum oxygen uptake for elite athletes has been found to be 60 with a standard deviation of 7.2. assume that the distribution is approximately normal.

What is the y intercept of f(x)=(1/2)^x?