Arizona State University ECN 221- Exam 2 Questions with Answes and Answer Key. Most Commonly Tested MCQ. Contains 30 questions.

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Practice Exam 2 Spring 2014 Name MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) When the discrete random variable is expressed in terms of... dollars, the mean of the distribution is known as the A) expected value of the distribution. B) expected monetary value. C) expected value of sample information. D) average value of the distribution. 2) A novel on the Amazon.com web site has the following ratings, in number of stars, from reviewers: Number of Stars Frequency 1 2 2 9 3 12 4 18 5 9 What is the mean of this distribution? A) 3.10 B) 3.95 C) 3.46 D) 2.87 3) A novel on the Amazon.com web site has the following ratings, in number of stars, from reviewers: Number of Stars Frequency 1 2 2 9 3 12 4 18 5 9 What is the standard deviation of this distribution? A) 3.19 B) 1.10 C) 2.56 D) 4.60 4) A novel on the Amazon.com web site has the following ratings, in number of stars, from reviewers: Number of Stars Frequency 1 2 2 9 3 12 4 18 5 9 What is the probability that a randomly selected review is more than 3 stars? A) 0.24 B) 0.30 C) 1.00 D) 0.54 1 1) 2) 3) 4)5) According to LIMRA, 77% of husband-wife families with kids under 18 years old have life insurance. A random sample of six husband-wife families was selected. What is the probability that exactly four families have life insurance? A) 0.5215 B) 0.2789 C) 0.4832 D) 0.3735 6) According to LIMRA, 77% of husband-wife families with kids under 18 years old have life insurance. A random sample of six husband-wife families was selected. What is the probability that less than two families have life insurance? A) 0.1197 B) 0.1864 C) 0.0029 D) 0.0569 7) According to LIMRA, 77% of husband-wife families with kids under 18 years old have life insurance. A random sample of six husband-wife families was selected. What is the mean of this distribution? A) 5.86 B) 3.50 C) 5.28 D) 4.62 8) A _ distribution is useful for calculating the probability that a certain number of events will occur over a specific interval of time or space. A) hypergeometric B) binomial C) normal D) Poisson 5) 6) 7) 8) 9) The mean and the variance are equal for a probability distribution. 9) A) Poisson B) normal C) binomial D) uniform 10) A company that bakes chocolate chip cookies averages 5.2 chocolate chips per cookie. Assume that the number of chocolate chips per cookie follows the Poisson distribution. What is the probability that a randomly selected cookie will contain exactly four chocolate chips? A) 0.1681 B) 0.3325 C) 0.2254 D) 0.2960 11) A company that bakes chocolate chip cookies averages 5.2 chocolate chips per cookie. Assume that the number of chocolate chips per cookie follows the Poisson distribution. What is the probability that a randomly selected cookie will contain two or more chocolate chips? A) 0.5469 B) 0.4401 C) 0.3569 D) 0.9658 10) 11) 12) The probability distribution is bell-shaped and symmetrical. 12) A) normal B) uniform C) binomial D) Poisson 13) A smaller standard deviation for the normal probability distribution results in 13) A) a fatter curve that is more spread out around the mean and not as tall. B) a skinnier curve that is more spread out around the mean and not as tall. C) a fatter curve that is tighter and taller around the mean. D) a skinnier curve that is tighter and taller around the mean. 14) Which of the following statements is true regarding z-scores for the normal probability distribution? A) z-scores are equal to 1.0 for values of x that are equal to the distribution mean. B) z-scores are zero for values of x that are less than the distribution mean. C) z-scores are negative for values of x that are less than the distribution mean. D) z-scores are positive for values of x that are less than the distribution mean. 2 14)15) The time for a professor to grade an exam is normally distributed with a mean of 12.6 minutes and a standard deviation of 2.5 minutes. What is the probability that a randomly selected exam will require less than 16 minutes to grade? A) 0.7734 B) 0.9131 C) 0.5910 D) 0.1401 16) The time for a professor to grade an exam is normally distributed with a mean of 12.6 minutes and a standard deviation of 2.5 minutes. What is the probability that a randomly selected exam will require between 11 and 15 minutes to grade? A) 0.5704 B) 0.9637 C) 0.7567 D) 0.4875 15) 16) 17) The shape of the uniform probability distribution is 17) A) right-skewed. B) flat. C) left-skewed. D) symmetrical. 18) The time that customers wait to be served at the delicatessen for a grocery store follows the uniform distribution between 0 and 7 minutes. What is the mean of this distribution? A) 2.5 B) 1.5 C) 3.5 D) 4.5 19) The time that customers wait to be served at the delicatessen for a grocery store follows the uniform distribution between 0 and 7 minutes. What is the probability that a randomly selected customer will wait between 1 and 5 minutes at the deli? A) 0.5714 B) 0.4286 C) 0.1429 D) 0.2857 20) The time that customers wait to be served at the delicatessen for a grocery store follows the uniform distribution between 0 and 7 minutes. What is the probability that a randomly selected customer will wait will be exactly 5 minutes at the deli? A) 0.2857 B) 0.0 C) 0.4286 D) 0.7143 21) Consider the following population which represents the years of teaching experience of the 24 full-time business faculty at Wesley College. Using the first row of data as a sample, the sampling error is . A) 0.80 B) 1.40 C) -0.50 D) -1.20 18) 19) 20) 21) 22) errors can occur as a result of a questionnaire that contains ambiguous questions. 22) A) Judgment B) Nonsampling C) Sampling D) Nonprobability 323) The Central Limit Theorem (CLT) states that the 23) A) sample means of large-sized samples will be normally distributed regardless of the shape of their population distributions. B) sample means of large-sized samples will be uniformly distributed regardless of the shape of their population distributions. C) sample means of any samples will be normally distributed regardless of the shape of their population distributions. D) sample means of any samples will be uniformly distributed regardless of the shape of their population distributions. 24) For a sample size of two or more, the standard error of the mean must be 24) A) less than the population standard deviation. B) more than the population mean. C) less than the population mean. D) equal to the population standard deviation. 25) ClearBags is an online company that sells packaging materials for photographers. Suppose their average order size is $210.18 with a standard deviation of $64.21. A random sample of 32 customer orders has been selected. The standard error of the mean for this sample is . A) $64.21 B) $11.35 C) $15.80 D) $25.40 26) An Epson inkjet printer ad advertises that the black ink cartridge will provide enough ink for an average of 245 pages. Assume that this claim is accurate and that the standard deviation for this population is 15 pages. A random sample of 33 customers was surveyed about the number of pages they were able to print with their black ink cartridges. What the probability that the sample mean will be 246 pages or less? A) 0.6480 B) 0.1093 C) 0.8729 D) 0.3520 27) Suppose the local Best Buy store averages 522 customers per day entering the facility with a standard deviation of 124 customers. A random sample of 40 business days was selected. What is the probability that the average number of customers in the sample is between 530 and 540? A) 0.3057 B) 0.2387 C) 0.0572 D) 0.1621 28) The average battery life of the iPhone 4S is reported to be 6.0 hours. Assume that the standard deviation for the battery life for this cell phone is 45 minutes. A random sample of 42 iPhones had an average battery life of 5.86 hours. Which of the following statements is correct? A) The interval that contains 95% of the sample means is 5.09 and 6.90 hours. Because the sample mean is between these two values, we have support that the average battery life equals 6.0 hours. B) The interval that contains 95% of the sample means is 5.09 and 6.90 hours. Because the sample mean is not between these two values, we have support that the average battery life equals 6.0 hours. C) The interval that contains 95% of the sample means is 6.0 and 6.5 hours. Because the sample mean is not between these two values, we do not have support that the average battery life equals 6.0 hours. D) The interval that contains 95% of the sample means is 5.77 and 6.23 hours. Because the sample mean is between these two values, we have support that the average battery life equals 6.0 hours. 4 25) 26) 27) 28)29) According to IDC, Apple's share of the smartphone market was 20% during the 3rd quarter of 2011. A random sample of 115 smartphone users was selected. The standard error of the proportion is . A) 0.1016 B) 0.0157 C) 0.0690 D) 0.0373 30) According to the National Center for Health Statistics, 17% of adults between the ages of 45 and 64had taken statin drugs in the prior 30 days to reduce cholesterol levels. A random sample of 120adults from this age group was selected. What is the probability that between 24 and 27 from this sample had taken statin drugs during the last 30 days? A) 0.1373 B) 0.3026 C) 0.4478 D) 0.1892 Answer Key [Show More]

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