- 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**

Select the correct statement(s).

II. The t-score is used when the sample size is 30 or more and you know the population standard deviation.

III. Increasing the confidence level while keeping other values constant will keep the width of the interval unchanged.

I. The main difference between the t and z statistic is that the t statistic has a mean of 1 and the z statistic has a mean of 0.

II. The t-score is used when the sample size is 30 or more and you know the population standard deviation.

III. Increasing the confidence level while keeping other values constant will keep the width of the interval unchanged.

Correct Answer: None of these statements is correct.

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