The whole scenario is totally dependent on the probability of a potential victim being able to kill the zombie before being bitten. In some places, the zombies would win. In other places, people would be able to shoot the zombies.
It also depends on how hard to kill the zombies are (Will one fall with a shot that would kill a normal human? Will one only fall from a head shot? Is it a supernatural zombie which requires complete dismemberment?)
The whole scenario is totally dependent on the probability of a potential victim being able to kill the zombie before being bitten. In some places, the zombies would win. In other places, people would be able to shoot the zombies.
They did a follow up study that considered defense. Guess what? Humanity won.
It was just a study to show who epidemics worked for a class. Nothing serious.
WRONG
The scenario depends on whether the zombies are “fast zombies” such as in World War Z or “slow zombies” such as in The Walking Dead.
I hate fast zombies.