- CFA Exams
- CFA Level I Exam
- Study Session 3. Quantitative Methods (2)
- Reading 9. Common Probability Distributions
- Subject 8. The Standard Normal Distribution

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**CFA Practice Question**

The amount of fill in a certain brand of bottled water is normally distributed with a mean of 16 ounces and a standard deviation of .25 ounce. What is the probability that a bottle has more than 16.25 ounces?

B. 0.3413

C. 0.6587

A. 0.1587

B. 0.3413

C. 0.6587

Correct Answer: A

The z-value corresponding to 16.25 is computed as: z = (16.25 - 16)/0.25 = 1.00. P(Z>=1.00) = 1 - P(Z <=1.00) = 1 - 0.8413 = 0.1587

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**User Contributed Comments**
6

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

JimM |
16.25 ounces is positive one SD. 68% of all fall within one SD, so 32% fall more than one SD away. Half are positive (above mean) and half are negative (below mean), so 16% chance of more than 16.25 ounces, so A. |

TammTamm |
I guessed at A. It seemed like the only logical answer. I hope guessing works on the exam. |

jansen1979 |
1SD above mean. 1-0.68 = .32/2 = .16 |

bundy |
Just as easy to say that there is a 84.13% chance of being within 16.25. 1 - .8413 = .1587 chance of being outside of 16.25 |

sgossett86 |
empirical rule |

Rachelle3 |
I wonder in the actual test instead of giving us the Stan dev it tells us the variance then from there we would need to sq root the variance to get the stan dev before doing the formula like analystnotes shows? hmmm...... |