- CFA Exams
- CFA Level I Exam
- Topic 1. Quantitative Methods
- Learning Module 5. Sampling and Estimation
- Subject 5. Confidence Intervals for the Population Mean and Selection of Sample Size

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**CFA Practice Question**

What assumption is made when calculating a confidence interval around the mean for a sample with less than 30 data points?

II. The population from which the sample was taken is normally distributed.

III. The sample standard deviation is equal to the population standard deviation.

I. The sample is normally distributed.

II. The population from which the sample was taken is normally distributed.

III. The sample standard deviation is equal to the population standard deviation.

Correct Answer: II

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**User Contributed Comments**
2

User |
Comment |
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MFTIOA |
If Nonnormal and small sample, then a confidence interval can't be constructed |

ashish100 |
Thanks MFTIOA! cool name! |