Step 1 :Given that the proportion (p) of users who reported dizziness as a side effect is 0.67 and the sample size (n) is 100.
Step 2 :The standard deviation of a proportion is calculated using the formula \(\sqrt{p(1-p)/n}\). Substituting the given values, we get \(\sqrt{0.67(1-0.67)/100} = 0.04702127178203499\).
Step 3 :The z-score is calculated using the formula \((x - μ) / σ\), where x is the value of the element, μ is the mean, and σ is the standard deviation. In this case, since we are dealing with proportions, the mean is the proportion itself, so the z-score would be \((0.67 - 0.67) / 0.04702127178203499 = 0\).
Step 4 :Final Answer: The z-score is \(\boxed{0}\).