Chapter 2

# Chapter 2 - Chapter 2: The Normal Distributions Use the...

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Chapter 2: The Normal Distributions Use the following to answer questions 1-3: 1. For this density curve, which of the following is true? A) It is symmetric. C) The median is 1. B) The total area under the curve is 1. D) All of the above. Ans: D Section: 2.1 Density Curves and The Normal Distributions 2. For this density curve, what percentage of the observations lies above 1.5? A) 25%. B) 50%. C) 75%. D) 80%. Ans: A Section: 2.1 Density Curves and The Normal Distributions 3. For the density curve shown on the previous page, what percentage of the observations lies between 0.5 and 1.2? A) 25%. B) 35%. C) 50%. D) 70%. Ans: B Section: 2.1 Density Curves and The Normal Distributions Page 21

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Chapter 2: The Normal Distributions 4. For the density curve displayed below, the mean is A) 0.25. B) 0.50. C) 0.71. D) 0.75. Ans: B Section: 2.1 Density Curves and The Normal Distributions 5. A normal density curve has which of the following properties? A) It is symmetric. B) It has a peak centered above its mean. C) The spread of the curve is proportional to the standard deviation. D) All of the above. Ans: D Section: 2.1 Density Curves and The Normal Distributions 6. Items produced by a manufacturing process are supposed to weigh 90 grams. The manufacturing process is such, however, that there is variability in the items produced and they do not all weigh exactly 90 grams. The distribution of weights can be approximated by a normal distribution with mean 90 grams and a standard deviation of 1 gram. Using the 68–95–99.7 rule, what percentage of the items will either weigh less than 87 grams or more than 93 grams? A) 6%. B) 94%. C) 99.7%. D) 0.3%. Ans: D Section: 2.1 Density Curves and The Normal Distributions Page 22
Chapter 2: The Normal Distributions 7. For the density curve below, which of the following is true? A) The mean and median are equal. B) The mean is greater than the median. C) The mean is less than the median. D) The mean could be either greater than or less than the median. Ans: C Section: 2.1 Density Curves and The Normal Distributions 8. A normal density curve has which of the following properties? A) It is symmetric. B) It has a peak centered above its mean. C) The spread of the curve is proportional to the standard deviation. D) All of the above.

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## This note was uploaded on 03/30/2008 for the course STAT 155 taught by Professor Unknown during the Spring '07 term at UNC.

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Chapter 2 - Chapter 2: The Normal Distributions Use the...

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