Which of these graphs represents a function?

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 square root of 45? (step by step working plz)

[tex]5 \times1 \frac{12}{13} [/tex] me