CFA Practice Question

There are 434 practice questions for this study session.

CFA Practice Question

Which statement(s) regarding the selection of an appropriate sample size is (are) false?

I. If the population is normally distributed and the population variance is known, use a t-score irrespective of sample size.
II. If the population is normally distributed and the population variance is unknown, use a z-score irrespective of sample size.
III. If the population is not normally distributed and the population variance is known, use a F-score only if n >= 30; otherwise it cannot be done.
IV. If the population is not normally distributed and the population variance is unknown, use a X2-score only if n >= 30; otherwise it cannot be done.
A. I and II
B. II, III and IV
C. I, II, III and IV
Explanation: All these statements are false. The correct statements would have been:
  • If the population is normally distributed and the population variance is known, use a z-score irrespective of sample size.
  • If the population is normally distributed and the population variance is unknown, use a t-score irrespective of sample size.
  • If the population is not normally distributed and the population variance is known, use a z-score only if n >= 30; otherwise it cannot be done.
  • If the population is not normally distributed and the population variance is unknown, use a t-score only if n >= 30; otherwise it cannot be done.

User Contributed Comments 4

User Comment
kellyyang population variance unknown, using t-score
population variance known, using z-score

population variance known, if n>30, using z-score
population variance unknown, if n<30, using t-score
kellyyang SOrry one i typed wrong. correct is n>30, using t-score for unknown.
lordcomas Memorize these 4 bullet points and you will be safe for answering related questions.
swkimpo For reference, F-score is used to determine whether two variances are the same. A chi-square score is used to test a single variance.
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