Chapter 7 Quiz practice Other
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| Chapter 7 Quiz practice
Other 1.For each description below, identify each underlined number as a parameter or statistic. Use appropriate notation to describe each number, e.g., . (a) Nationwide, 84% of people are living in the same house they were living in one year ago. The town council of Pleasant Valley surveys 100 residents and find that 75% of them have not moved in the past year. (b) The mean birthweight of infants in the United States in 2006 was 3.3 kg with a standard deviation of 0.57 kg. An obstetrician determines that among her own patients, the mean birthweight was 3.6 kg. 2. The service department of a large automobile dealership keeps records of the odometer readings of cars that it repairs and determines that the distribution of miles driven per year by all of its customers has a mean of 14,000 miles and a standard deviation of 4000. The distribution is skewed to the right. Suppose a random sample of 12 cars is taken from the hundreds of cars for which they have records, and mean number of miles per year, is calculated. (a) What is the mean of the sampling distribution of ? (b) Is it possible to calculate the standard deviation of ? If it is, do the calculation. If it isn’t, explain why. (c) Do you know the approximate shape of the sampling distribution of ? If so, describe the shape and justify your answer. If not, explain why not. 3. Inexpensive bathroom scales are not consistently accurate. A manufacturer of bathroom scales says that when a 150 pound weight is placed on all the scales produced in his factory, the weight indicated by the scales is Normally distributed with a mean of 150 pounds and a standard deviation of 2 pounds. A consumer advocacy group acquires a randomly-selected group of 12 scales from the manufacturer and weighs a 150 weight on each one. They get a mean weight of 151 pounds, which makes them suspicious about the company’s claim. To test this, they use a computer to simulate 200 samples of 12 scales from a population with a mean of 150 pounds and standard deviation 2 pounds. Below is a dotplot of the means from these 200 samples. 
(a) What is the population in this situation, and what population parameters have we been given? (b) The distribution of one sample is described in the opening paragraph. What information have we been given about this sample? (c) Is the dotplot above a sampling distribution? Explain. (d) Do you think the manufacturer is being honest about the accuracy of its bathroom scales? Justify your answer. 4. According to a poll, 22% of high school students in the United Kingdom say that Dobby is their favorite character in the Harry Potter books. Let’s assume this is the parameter value for the entire population of high school students in the U.K. You take a sample of 150 high school students and record the proportion, , of individuals in your sample who say Dobby is their favorite character.
(b) What is the approximate shape of the sampling distribution? Justify your answer. (c) Suppose our sample size was 36 instead of 150. Compare the shape, center, and spread of this sampling distribution to the one in parts A. and B.. (d) A small town in the U.K. has only 600 high school students. What is the largest possible sample you can take from this town and still be able to calculate the standard deviation of the sampling distribution of using the method presented in the textbook? Explain. Chapter 7 Quiz practice Answer Section OTHER 1. ANS: A. p=0.84 is a parameter; is a statistic. B. kg is a parameter; kg is a parameter; kg is a statistic PTS: 1
A. miles (the same as the population mean). B. Yes. It seems reasonable to assume that the sample of 12 is less than 10% of the entire population of customers’ cars. PTS: 1
A. The population is all bathroom scales produced by the manufacturer. We’ve been given the population mean pounds and the population standard deviation pounds. B. The sample mean is pounds and the sample size is n=12 C. No, it’s merely an approximation of a sampling distribution generated by simulating 200 sample means. The actual sampling distribution includes the means form all possible samples of size 12 from the population—many more than 200 values. D. Only 8 out of 200, or 4% of the sample means in our simulation are as far or farther above 150 pounds as our sample was. If the population mean is really 150 pounds, then our sample is unusual, and we should be somewhat suspicious about the manufacturer’s claim. PTS: 1
A. D. The largest sample we can take is 60, otherwise the sample would be more than 10% of the population, and sampling without replacement would require a finite population correction to calculate standard deviation. PTS: 1 Directory: cms -> lib -> TX01001414 -> Centricity -> Domain lib -> 1. naclo 2017 – North American Computational Linguistics Olympiad lib -> Chem I honors Unit 2 Notes: Numbers in Chemistry Measurement lib -> Sanderson High School ap human Geography Summer Assignment 2016 lib -> Find fantastic ousd elementary music programs lib -> American Studies Pacing Calendar 2014-2015 lib -> The ap history Timeline 8000bce-the Present lib -> Absolutism in Europe Domain -> Western Europe – Physical Geography Landforms and Waterways (1) Download 36.17 Kb. Share with your friends:
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. C. No. The population distribution is skewed, and n = 12, which is not large enough for the central limit theorem to apply.
B. Since np = (150)(0.22) = 33 10 and n(1-p) = 150(.78) - 117 10, the distribution is approximately normal. C.