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Ch. 3 - Describing, Exploring, and Comparing Data
Triola - Elementary Statistics 14th Edition
Triola14th EditionElementary StatisticsISBN: 9780137366446Not the one you use?Change textbook
Chapter 3, Problem 3.1.11

Critical Thinking. For Exercises 5–20, watch out for these little buggers. Each of these exercises involves some feature that is somewhat tricky. Find the (a) mean, (b) median, (c) mode, (d) midrange, and then answer the given question.


Smart Thermostats Listed below are selling prices (dollars) of smart thermostats tested by Consumer Reports magazine. If you decide to buy one of these smart thermostats, what statistic is most relevant, other than the measures of central tendency?


250 170 225 100 250 250 130 200 150 250 170 200 180 250

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Step 1: Organize the data set. Begin by listing all the selling prices in ascending order to make calculations easier. The sorted data set is: 100, 130, 150, 170, 170, 180, 200, 200, 225, 250, 250, 250, 250, 250.
Step 2: Calculate the mean. The mean is the average of the data set. Use the formula: xn, where x is the sum of all data points and n is the number of data points.
Step 3: Calculate the median. The median is the middle value when the data set is ordered. If the number of data points is odd, the median is the middle value. If even, it is the average of the two middle values. Identify the middle values in the sorted data set and compute accordingly.
Step 4: Determine the mode. The mode is the value that appears most frequently in the data set. Count the frequency of each value in the sorted data set and identify the value(s) with the highest frequency.
Step 5: Calculate the midrange. The midrange is the average of the minimum and maximum values in the data set. Use the formula: (min+max)2. Then, consider the question about the most relevant statistic other than measures of central tendency. Reflect on variability measures like range or standard deviation, which provide insights into the spread of the data.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Measures of Central Tendency

Measures of central tendency, including the mean, median, and mode, summarize a set of data by identifying the central point within that dataset. The mean is the average value, the median is the middle value when data is ordered, and the mode is the most frequently occurring value. Understanding these measures helps in interpreting data distributions and making informed decisions based on typical values.
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Variability

Variability refers to how spread out or dispersed the values in a dataset are. Common measures of variability include range, variance, and standard deviation. Analyzing variability is crucial because it provides insight into the consistency of the data and helps identify potential outliers, which can significantly affect the interpretation of central tendency measures.
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Contextual Relevance of Statistics

The relevance of a statistic depends on the context in which it is applied. In the case of purchasing smart thermostats, factors such as price range, consumer reviews, and energy efficiency may be more pertinent than just the average price. Understanding the context allows for a more comprehensive analysis and better decision-making based on the data presented.
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Related Practice
Textbook Question

In Exercises 21–24, find the mean and median for each of the two samples, then compare the two sets of results.


It’s a Small Wait After All Listed below are the wait times (minutes) at 10 AM for the rides “It’s a Small World” and “Avatar Flight of Passage.” These data are found in Data Set 33 “Disney World Wait Times.” Does a comparison between the means and medians reveal that there is a difference between the two sets of data?

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Textbook Question

Critical Thinking. For Exercises 5–20, watch out for these little buggers. Each of these exercises involves some feature that is somewhat tricky. Find the (a) mean, (b) median, (c) mode, (d) midrange, and then answer the given question.


Caffeine in Soft Drinks Listed below are measured amounts of caffeine (mg per 12 oz of drink) obtained in one can from each of 20 brands (7-UP, A&W Root Beer, Cherry Coke, . . . , Tab). Are the statistics representative of the population of all cans of the same 20 brands consumed by Americans?


0 0 34 34 34 45 41 51 55 36 47 41 0 0 53 54 38 0 41 47

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Textbook Question

Trimmed Mean Because the mean is very sensitive to extreme values, we say that it is not a resistant measure of center. By deleting some low values and high values, the trimmed mean is more resistant. To find the 10% trimmed mean for a data set, first arrange the data in order, then delete the bottom 10% of the values and delete the top 10% of the values, then calculate the mean of the remaining values. Use the axial loads (pounds) of aluminum cans listed below (from Data Set 41 “Aluminum Cans” in Appendix B) for cans that are 0.0111 in. thick. An axial load is the force at which the top of a can collapses. Identify any outliers, then compare the median, mean, 10% trimmed mean, and 20% trimmed mean.


247 260 268 273 276 279 281 283 284 285 286 288

289 291 293 295 296 299 310 504

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Textbook Question

Large Data Sets from Appendix B. In Exercises 25–28, refer to the indicated data set in Appendix B. Use software or a calculator to find the means and medians.


Body Temperatures Refer to Data Set 5 “Body Temperatures” in Appendix B and use the body temperatures for 12:00 AM on day 2. Do the results support or contradict the common belief that the mean body temperature is 98.6oF?

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Textbook Question

In Exercises 5–20, find the range, variance, and standard deviation for the given sample data. Include appropriate units (such as “minutes”) in your results. (The same data were used in Section 3-1, where we found measures of center. Here we find measures of variation.) Then answer the given questions.


Jaws 3 Listed below are the number of unprovoked shark attacks worldwide for the last several years. What extremely important characteristic of the data is not considered when finding the measures of variation?


70 54 68 82 79 83 76 73 98 81

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Textbook Question

In Exercises 21–28, use the same list of cell phone radiation levels given for Exercises 17–20. Find the indicated percentile or quartile.


P50


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