- CFA Exams
- CFA Level I Exam
- Topic 1. Quantitative Methods
- Learning Module 7. Estimation and Inference
- Subject 2. The Central Limit Theorem and Inference

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**CFA Practice Question**

The time that it takes to find a taxi when leaving a restaurant follows a left skewed distribution with a mean of 12 minutes and a standard deviation of 3 minutes. If 100 restaurant patrons are randomly sampled as to the amount of time that it takes for them to find a taxi, what type of sample distribution will be yielded?

A. left-skewed distribution; mean = 12 minutes; standard deviation = 0.3 minutes

B. normal distribution; mean = 12 minutes; standard deviation = 0.3 minutes

C. normal distribution; mean = 12 minutes; standard deviation = 3 minutes

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**User Contributed Comments**
8

User |
Comment |
---|---|

george2006 |
the problem is unclear on whether is the distribution is for the mean of the wait time or the values of the wait times. If it is the mean of the sample wait times, it will be NORMAL. Later it should be skewed. |

Carol1 |
it asked value of waiting time |

mrdavis |
std dev/n = 3/100 = .3 |

Nightsurfer |
std dev/n^1/2 = 3/100^1/2 = .3 |

xavi |
If the population standard deviation is known, then the standard deviation of the sample is found by dividing the population standard deviation by the square root of "n." |

nandobela |
n>30(large sample) normal distribution |

toyo |
sample mean=12, sample variance=3*3/100=0.09 sample standard deviation=0.3 |

endurance |
No need to do calculations here, the central limit theorem applies for sample tests -> mean = 12 and stddev = 0.3 no matter what how the population looks like |