You assume it has fatter tails. And it has fatter tails, because you're essentially underestimating the standard deviation over here. Anyway, with all of that said, let's just actually go through this problem. So we need to think about a 95% confidence interval around this mean right over here. So a 95% confidence interval, if this was a normal distribution, you would just look it up in a z table. But it's not. This is a t distribution.