The probability that any given man, including your friend's father, takes size 9 shoes is the same as the percentage provided in the survey. Since the survey indicates that 28% of all men take size 9 shoes, the probability can be expressed as:
\[ P(\text{size 9}) = 0.28 \]
So, the probability that your friend's father takes size 9 shoes is 0.28, or 28%.