Common Probability Distributions那章的LOS: Construct and explain confidence intervals for a normally distributed random variable里面说:
the 90 percent condidence interval for X is X-bar -1.65s to X-bar +1.65s.
(这里用的是Standard deviation)

Sampling and estimation那章的LOS: Identify and describe the desirable properties of an estimator里面说:
a confidence interval for the population mean can be calculated as:
x-bar +/- z*(stand error of the mean)

印象中,上学时构建confidence interval时,一直就使用的是standard error, 那上面使用standard deviation的公式是怎么来的呢?

but which stats i need to put into the formula if i meet this kind of question in the exam?

认真看题就好了，如果题目说的是对总体进行描述性统计，比如一个总体，均值方差告诉，问你置信区间，就用sd。相反抽样统计，则用se，比如一个样本，均值和方差已知，就用se。关键是分清总体还是样本。

是不是这样呢:

在Common Probability Distributions那个Session中,有这样一个例题:
Using a 20-year sample, the average return of a mutual fund has been 10.5 percent per year with a standard deviation of 18 percent. what is the 95 percent confidence interval for the mutual fund return next year?
因为题目给的是样本的均值和SD,所以answer中用的是SD.

相反,在Sampling and estimation中,confidence interval那个例题中:
Consider a practive esam that was administered to 100 Level 1 candidates...Assuming a population standard deviation equal to 15...
因为这里讲的是population SD,所以要用SE?