We defined that \alpha is the significance level. 1 - \alpha is defined as confidence level. z-score we denoted as z_{\alpha/2}. Since the question stats that we have 99% of confidence level, it means that significance \alpha = 0.01. Thus, we should look for an answer that has z_{0.005} in it, but we only have answers that denote either z_{1 - \alpha} or z_{(1-\alpha)/2}. Is that a mistake or intended inconsistency between the lecture and the quiz? What’s the correct notation?

Hi!

Thanks for noticing this, this is indeed a inconsistency. We have already fixed it.

Thanks,

Lucas