Unformatted text preview: s of these chocolate bars is claimed to be Normal with a mean of 8.1 oz and a standard deviation of 0.1 oz. 75. A) A quality control manager initially plans to take a simple random sample of size n from the production line. If he were to double his sample size (to 2n), by what factor would the standard deviation of the sampling distribution of X change? C) 2 1/2 B) 1 2 D) 2 16 J Diaco Elements of Statistics I Supplemental Final Exam Review 76. A) B) C) D) The quality control manager plans to take a simple random sample of size n from the production line. How big should n be so that the sampling distribution of X has standard deviation 0.01 oz? 10 100 1000 Cannot be determined unless we know the population follows a Normal distribution. 77. A) B) C) D) 78. A) B) C) D) E) If the quality control manager takes a simple random sample of ten chocolate bars from the production line, what is the probability that the sample mean weight of the ten sampled chocolate bars will be less than 8.0 oz? 0 0.00078 0.0316 0.1587 A sample of size n is selected at random from a population that has mean μ and standard deviation σ . The sample mean x will be determined from the observations in the sample. Which of the following statements about the sample mean, x , is (are) TRUE? The mean of x is the same as the population mean, i.e., μ . The variance of x is σ 2 n . The standard deviation of x decreases as the sample size grows larger. All of the above are true. Only A and B are true. 79. A) B) C) D) E) In the construction industry, compressive strength of concrete is a crucial characteristic. Suppose for a particular residential construction job the concrete tested after 3 days should have a mean compression strength of μ = 3000 psi with a standard deviation of σ = 50 psi. It is known that compressive strength of concrete is Normally distributed. On a construction site a sample of n = 5 specimens is selected and tested after 3 days. If the concrete has the desired characteristics what is the probability that the sample mean x will be larger than 3060 psi? 0.996 0.004 0.885 0.115 Unable to determine because the sample size n = 5 is much too small to rely on the Normal distribution for calculation of the required probability. Use the following to answer questions 80 and 81: During the summer months, the prices of nonsmoking rooms with a king‐size bed in hotels in a certain area are roughly Normally distributed with a mean of $131.80 and a standard deviation of $29.12. 80. What percentage of nonsmoking rooms with a king‐size bed cost more than $150? A) 0.77% C) 26.60% B) 11.25% D) 36.78% 17 J Diaco Elements of Statistics I Supplemental Final Exam Review 81. A) B) A travel agent randomly selects prices of nonsmoking rooms with a king‐size bed from 15 hotels in the area. What is the probability that their average cost will be more than $150? 0.0077 C) 0.2660 0.1125 D) 0.3678 Use the following to answer questions 82–84: The distribution of the amount of money undergraduate students spend on books for a term is slightly right‐skewed, with a mean of $400 and a standard deviation of $80. 82. If a student is selected at random, what is the probability that this student spends more than $425 on books? A) 0.1125 B) 0.3773 C) 0.6227 D) This cannot be determined from the information given. 83. In a simple random sample of 100 undergraduate...
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- Summer '09
- Statistics, J Diaco, Supplemental Final Exam