According to their answer, a 99% confidence interval extends 3 standard deviations either side of the mean. I thought it extended 2.58 standard deviations? Did anyone else get this question wrong because of this? What am I missing?

A number of participants on this board have pointed out the CFA’s loose rounding on this matter. They seem to think in this case that 2.58 ~ 3, which I think everyone agrees is fairly odd. Hopefully there will not be a question on the test that offers up both the 2.58 and the 3 solutions as potential answers.

just be safe on the exam, if you don’t see an answer for 2.58, then use 3 and try it again…also, when I did that question, I used 2.58, and the correct answer was still closest to the answer I calculated, so I still picked the right answer, I doubt they’ll put both 2.58 and 3 on the same question just to screw you…but you never know also, keep in mind this rule only works for normal distribution, if it’s some other distribution where we have to use central limit theorem, then it’s also the values on the z table