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Elementary Statistics 12th Edition Mario F. Triola - Solutions

In a USA Today survey, 20.8% of 144 respondents said that they aspired to have their boss’s job. Construct a 95% confidence interval estimate of the percentage of all workers who aspire to have their boss’s job. How are the results affected by the additional knowledge that the respondents chose
In a Harris poll of 514 human resource professionals, 45.9% said body piercings and tattoos were big grooming redflags.a. Among the 514 human resource professionals who were surveyed, how many of them said body piercings and tattoos were big grooming redflags?b. Construct a 99% confidence interval
In a Harris poll of 514 human resource professionals, 90% said the appearance of a job applicant is most important for a good first impression.a. Among the 514 human resource professionals who were surveyed, how many of them said the appearance of a job applicant is most important for a good first
The Mars candy company claims 13% of its M&M candies are brown, but Data Set 20 in Appendix B lists data from 100 M&Ms, and 8% of them are brown. Use the sample data to construct a 98% confidence interval estimate of the proportion of brown M&Ms. Does it appear the claimed rate of 13% rate is
Misleading Survey Responses In a survey of 1002 people, 70% said they voted in a recent presidential election (based on data from ICR Research Group). Voting records show 61% of eligible voters actually did vote. a. Find a 98% confidence interval estimate of the proportion of people who say they
Cell Phones and Cancer A study of 420,095 Danish cell phone users found that 0.0321% of them developed cancer of the brain or nervous system. Prior to this study of cell phone use, the rate of such cancer was found to be 0.0340% for those not using cell phones. The data are from the Journal of the
Medication Usage In a survey of 3005 adults aged 57 through 85 years, it was found that 81.7% of them used at least one prescription medication (based on data from “Use of Prescription and Over-the-Counter Medications and Dietary Supplements Among Older Adults in the United States,” by Qato et
Republicans Find the sample size needed to estimate the percentage of Republicans among registered voters in California. Use a 0.03 margin of error, use a confidence level of 90%, and assume that pn and qn are unknown.
Find the sample size needed to estimate the percentage of robberies in Texas that result in arrests. Use a 0.04 margin of error, use a confidence level of 80%, and assume that pn and qn are unknown.
Tattooed Democrats Find the sample size needed to estimate the percentage of Democrats who have tattoos. Use a 0.05 margin of error, use a confidence level of 99%, and use results from a prior Harris poll suggesting that 15% of Democrats have tattoos.
Fortune Tellers Find the sample size needed to estimate the percentage of adults who have consulted fortune tellers. Use a 0.03 margin of error, use a confidence level of 98%, and use results from a prior Pew Research Center poll suggesting that 15% of adults have consulted fortune tellers.
You are the operations manager for American Airlines and you are considering a higher fare level for passengers in aisle seats. You want to estimate the percentage of passengers who now prefer aisle seats. How many randomly selected air passengers must you survey? Assume that you want to be 95%
You plan to develop a new software system that you believe will surpass the success of Google and Facebook combined. In planning for the operating system that you will use, you need to estimate the percentage of computers that use Windows. How many computers must be surveyed in order to be 99%
As manager for an advertising company, you must plan a campaign designed to increase Twitter usage. You want to first determine the percentage of adults who know what Twitter is. How many adults must you survey in order to be 90% confident that your estimate is within five percentage points of the
You have been given the task of estimating the percentage of Southwest flights that arrive on time, which is no later than 15 minutes after the scheduled arrival time. How many flights must you survey in order to be 80% confident that your estimate is within three percentage points of the true
Refer to Data Set 12 in Appendix B. Treat the data as a sample and find the proportion of presidents who were taller than their opponents. Use that result to construct a 95% confidence interval estimate of the population percentage. Based on the result, does it appear that greater height is an
Refer to Data Set 15 in Appendix B. A flight is considered on time if it arrives no later than 15 minutes after the scheduled arrival time. The last column of Data Set 15 lists arrival delays, so on-time flights correspond to values in that column that are 15 or less. Use the data to construct a
For Formulas 7-2 and 7-3 we assume that the population is infinite or very large and that we are sampling with replacement. When we have a relatively small population with size N and sample without replacement, we modify E to include the finite population correction factor shown here, and we can
Special tables are available for finding confidence intervals for proportions involving small numbers of cases, where the normal distribution approximation cannot be used. For example, given x = 3 successes among n = 8 trials, the 95% confidence interval found in Standard Probability and Statistics
Repeat Exercise using a 99% confidence level. What is unusual about the result? Does common sense suggest a modification of the result?
According to the Rule of Three, when we have a sample size n with x = 0 successes, we have 95% confidence that the true population proportion has an upper bound of 3>n. (See “A Look at the Rule of Three,” by Jovanovich and Levy, American Statistician, Vol. 51, No. 2.) a. If n independent
A one-sided claim about a population proportion is a claim that the proportion is less than (or greater than) some specific value. Such a claim can be formally addressed using a one-sided confidence interval for p, which can be expressed as p < p + E or p > p E, where the margin of error E is
Refer to the accompanying screen display.a. Express the confidence interval in the format that uses the €œless than€ symbol.b. Identify the best point estimate of m and the margin of error.
For the accompanying screen display, a simple random sample of size n = 40 was obtained from the population of duration times (seconds) of eruptions of the old Faithful geyser. a. What is the number of degrees of freedom that should be used for finding the critical value ta/2? b. Find the critical
The results in the screen display are based on a 95% confidence level. Write a statement that correctly interprets the confidence interval.
What does it mean when we say that the confidence interval methods of this section are robust against departures from normality? Does the dotplot below appear to satisfy the requirement of this section? Why or why not?
Data Set 16 in Appendix B lists the depths (km) of a sample of 50 earthquakes. Those 50 depths have a mean of 9.808kmanda standard deviation of 5.013 km. Construct a 98% confidence interval estimate of the mean of all such depths. Is the confidence interval affected by the fact that the data appear
Listed below are the amounts of mercury (in parts per million, or ppm) found in tuna sushi sampled at different stores in New York City. The study was sponsored by the New York Times, and the stores (in order) are D’ Agostino, Eli’s Manhattan, Fairway, Food Emporium, Gourmet Garage, Grace’s
Listed below are the recent annual compensation amounts (in thousands of dollars) for a random sample of chief executive officers (Mulally from Ford, Jobs from Apple, Kent from Coca-Cola, Otellini from Intel, and McNerney from Boeing). The mean of the sample is 12,898 (thousand dollars) and the
The Chapter Problem for Chapter 3 includes the numbers of chocolate chips in a sample of 40 Chips Ahoy regular cookies. The mean is 23.95 chocolate chips and the standard deviation is 2.55 chocolate chips. Construct a 99% confidence interval estimate of the mean number of chocolate chips in all
Data Set 3 in Appendix B includes a sample of 106 body temperatures having a mean of 98.20oF and a standard deviation of 0.62oF. Construct a 95% confidence interval estimate of the mean body temperature for the entire population. What does the result suggest about the common belief that 98.6oF is
In a test of weight loss programs, 40 adults used the Atkins weight loss program. After 12 months, their mean weight loss was found to be 2.1 lb, with a standard deviation of 4.8 lb. Construct a 90% confidence interval estimate of the mean weight loss for all such subjects. Does the Atkins program
Cholesterol In a test of the effectiveness of garlic for lowering cholesterol, 49 subjects were treated with raw garlic. Cholesterol levels were measured before and after the treatment. The changes (before minus after) in their levels of LDL cholesterol (in mg/dL) had a mean of 0.4 and a standard
A clinical trial was conducted to test the effectiveness of the drug zopiclone for treating insomnia in older subjects. Before treatment with zopiclone, 16 subjects had a mean wake time of 102.8 min. After treatment with zoplicone, the 16 subjects had a mean wake time of 98.9 min and a standard
Listed below are the gross amounts (in millions of dollars) earned from box office receipts for the movie Harry Potter and the Half-Blood Prince. The movie opened on a Wednesday, and the amounts are listed in order for the first 14 days of the movie’s release. Use the sample values to construct a
Listed below are the numbers of years it took for a random sample of college students to earn bachelor’s degrees (based on data from the National Center for Education Statistics). Construct a 90% confidence interval estimate of the mean time required for all college students to earn bachelor’s
Listed below are the measured radiation emissions (in W/kg) corresponding to these cell phones: Samsung SGH-tss9, Blackberry Storm, Blackberry Curve, Motorola Moto, T-Mobile Sidekick, Sanyo Katana Eclipse, Palm Pre, Sony Ericsson, Nokia 6085, Apple iPhone 3G S, Kyocero Neo E1100. The data are from
Listed below are the ages (years) of randomly selected race car drivers (based on data reported in USA Today). Construct a 98% confidence interval estimate of the mean age of all race car drivers. 32 32 33 33 41 29 38 32 33 23 27 45 52 29 25
Listed below are the lead concentrations (in mg/g) measured in different Ayurveda medicines. Ayurveda is a traditional medical system commonly used in India. The lead concentrations listed here are from medicines manufactured in the United States. The data are based on the article “Lead, Mercury,
Listed below are brain volumes (cm3) of unrelated subjects used in a study. Use the sample data to construct a 99% confidence interval estimate of the mean of the brain volume of the population. Given that typical brain volumes are between 950 cm3 and 1800 cm3, do these values appear to be
The accompanying stemplots depict ages of applicants who were unsuccessful in winning promotion and ages of applicants who were successful in winning promotion (based on data from €œDebating the Use of Statistical Evidence in Allegations of Age Discrimination€ by Barry and
Changes in head sizes over time suggest interbreeding with people from other regions. Use the data depicted in the accompanying dotplots and construct 95% confidence intervals to determine whether skull breadths (mm) appear to have changed from 4000 b.c. to 150 a.d. Explain your conclusion.
The Wechsler IQ test is designed so that the mean is 100 and the standard deviation is 15 for the population of normal adults. Find the sample size necessary to estimate the mean IQ score of professional pilots. We want to be 90% confident that our sample mean is within 3 IQ points of the true
As part of a study of grade inflation, you want to estimate the mean grade point average of all current college students in the United States. All grade point averages are to be standardized for a scale between 0 and 4. How many grade point averages must be obtained so that the sample mean is
Research of selling prices for used two-year-old Corvettes reveals that they have a standard deviation of $2157 (based on data from Edmunds.com). How many selling prices must you obtain in order to estimate the mean selling price of these cars? Assume that you want 98% confidence that your sample
You want to estimate the mean amount of time Internet users spend on Facebook each month. How many Internet users must be surveyed in order to be 95% confident that your sample mean is within 15 minutes of the population mean? Based on results from prior Nielsen survey, assume that the standard
You want to estimate the mean SAT score of all college applicants. First use the range rule of thumb to make a rough estimate of the standard deviation of those scores. Possible SAT scores range from 600 to 2400. Use the estimated standard deviation to determine the sample size corresponding to a
You want to estimate the mean amount of annual tuition being paid by current full-time college students in the United States. First use the range rule of thumb to make a rough estimate of the standard deviation of the amounts spent. It is reasonable to assume that tuition amounts range from $0 to
Refer to Data Set 1 in Appendix B and find the maximum and minimum pulse rates for males, then use those values with the range rule of thumb to estimates. How many adult males must you randomly select and test if you want to be 95% confident that the sample mean pulse rate is within 2 beats (per
Refer to Data Set 16 in Appendix B and find the maximum and minimum earthquake magnitudes, then use those values with the range rule of thumb to estimates. How many earthquakes must you randomly select if you want to be 95% confident that the sample mean magnitude is within 0.2 of the true
Use the earthquake magnitudes listed in Data Set 16 from Appendix B and construct a 99% confidence interval estimate of the mean of all such magnitudes. Find the sample size required to estimate the population mean.
Figure from Example 5 shows a graph of three different confidence intervals. Use the continue levels of smokers listed in Data Set 9 from Appendix B and construct the 95% confidence interval estimate of the population mean m.
Construct the confidence interval for Exercise assuming that s is known to be 5.013km. Find the confidence interval using the known value of S.
Construct the confidence interval for Exercise assuming that s is known to be 0.366 ppm. Find the confidence interval using the known value of S.
Construct the confidence interval for Exercise assuming that s is known to be 7718.8 thousand dollars. Find the confidence interval using the known value of S.
Construct the confidence interval for Exercise assuming that s is known to be 2.55 chocolate chips. Find the confidence interval using the known value of S.
If the first value of 3.0 in Exercise 21 is changed to 300, it becomes an outlier. Does this outlier have much of an effect on the confidence interval? How should you handle outliers when they are found in sample data sets that will be used for the construction of confidence intervals?
Finite Population Correction Factor If a simple random sample of size n is selected without replacement from a finite population of size N, and the sample size is more than 5% of the population size (n > 0.05N), better results can be obtained by using the finite population correction factor,
Confidence Interval for Sample of Size n  1 Based on the article “An Effective Confidence Interval for the Mean with Samples of Size One and Two,” by Wall, Boen, and Tweedie (American Statistician, Vol. 55, No. 2), a 95% confidence interval for m can be found (using methods not discussed
Using the 40 LDL cholesterol levels of women listed in Data Set 1, we get this 95% confidence interval estimate: 916.591 6 s2 6 2252.119, and the units of measurement are (mg/dL)2. Identify the corresponding confidence interval estimate of s and include the appropriate units. Given that the
The dotplot below depicts individual digits selected in the Pick 4 lottery from different states. Can the original list of individual sample digits be identified? Can the sample data be used to construct a 95% confidence interval estimate of the population standard deviation for all such digits?
What is different about the normality requirement for a confidence interval estimate of s and the normality requirement for a confidence interval estimate of µ?
Cigarettes 99% confidence; n = 25, s = 0.24 mg.Use the given information to find the number of degrees of freedom, the critical values X2L and X2R, and the confidence interval estimate of s. The samples are from Appendix B and it is reasonable to assume that a simple random sample has been selected
Weights of dollar Coins 99% confidence; n = 20, s = 0.04111 g.Use the given information to find the number of degrees of freedom, the critical values X2L and X2R, and the confidence interval estimate of s. The samples are from Appendix B and it is reasonable to assume that a simple random sample
Platelet Counts of Women 95% confidence; n = 40, s = 65.2.Use the given information to find the number of degrees of freedom, the critical values X2L and X2R, and the confidence interval estimate of s. The samples are from Appendix B and it is reasonable to assume that a simple random sample has
EarthquaTe Magnitufes 95% confidence; n = 50, s = 0.587.Use the given information to find the number of degrees of freedom, the critical values X2L and X2R, and the confidence interval estimate of s. The samples are from Appendix B and it is reasonable to assume that a simple random sample has been
Mean Bofy Temperature Data Set 3 in Appendix B includes a sample of 106 body temperatures having a mean of 98.20oF and a standard deviation of 0.62oF. Construct a 90% confidence interval estimate of the standard deviation of the body temperatures for the entire population.Assume that each sample is
The Chapter Problem for Chapter 3 includes the numbers of chocolate chips in a sample of 40 Chips Ahoy regular cookies. The mean is 23.95 and the standard deviation is 2.55. Construct a 90% confidence interval estimate of the standard deviation of the numbers of chocolate chips in all such cookies.
A container of car antifreeze is supposed to hold 3785mL of the liquid. Realizing that fluctuations are inevitable, the quality-control manager of the Taconic Chemical Company wants to be quite sure that the standard deviation is less than 30mL. Otherwise, some containers would overflow while
Data Set 1 in Appendix B includes 40 pulse rates of men, and those pulse rates have a mean of 67.3 beats per minute and a standard deviation of 10.3 beats per minute. That data set also includes 40 pulse rates of women, and those pulse rates have a mean of 77.5 beats per minute and a standard
Listed below are the amounts of mercury (in parts per million, or ppm) found in tuna sushi sampled at different stores in New York City. The study was sponsored by the New York Times, and the stores (in order) are D’ Agostino, Eli’s Manhattan, Fairway, Food Emporium, Gourmet Garage, Grace’s
Highway Speefs Listed below are speeds (mi/h) measured from southbound traffic on I-280 near Cupertino, California (based on data from Sig Alert). This simple random sample was obtained at 3:30 p.m. on a weekday. Use the sample data to construct a 95% confidence interval estimate of the population
Promotion and Age Listed below are ages of applicants who were unsuccessful in winning promotion and ages of applicants who were successful in winning promotion (based on data from €œDebating the Use of Statistical Evidence in Allegations of Age Discrimination€ by Barry and
a. Comparing Waiting Lines The values listed below are waiting times (in minutes) of customers at the Jefferson Valley Bank, where customers enter a single waiting line that feeds three teller windows. Construct a 95% confidence interval for the population standard deviation s. b. The values listed
Refer to Data Set 21 in Appendix B and use the weights of the post-1983 pennies to construct a 98% confidence interval estimate of the standard deviation of the weights of all post-1983 pennies.
Refer to Data Set 12 in Appendix B and use the ages (years) of the presidents at the times of their inaugurations. Treating the data as a sample, construct a 98% confidence interval estimate of the standard deviation of the population of all such ages.
In constructing confidence intervals for s or s2, Table A-4 can be used to find the critical values x2Landx2L only for select values of n up to 101, so the number of degrees of freedom is 100 or smaller. For larger numbers of degrees of freedom, we can approximate x2Landx2Lby usingwhere k is the
In a Gallup poll of 557 randomly selected adults, 284 said that they were underpaid. a. Identify the best point estimate of the percentage of all adults who say that they are underpaid. b. Construct a 95% confidence interval estimate of the percentage of all adults who say that they are
The author had difficulty finding the percentage of people who write with their left hand. If we want to estimate that percentage based on survey results, how many people must we survey in order to be 99% confident that we are within two percentage points of the population percentage? Assume that
There have been several studies conducted in an attempt to identify ways in which left-handed people are different from those who are right handed. Assume that you want to estimate the mean IQ of all left-handed adults. How many random left-handed adults must be tested in order to be 98% confident
Identify the distribution (normal, Student t, chi-square) that applies to each of the following situations. (If none of the three distributions is appropriate, then so state.) a. In constructing a confidence interval of m, you have 50 sample values and they appear to be from population with a
You have been hired by a college foundation to conduct a survey of graduates.a. If you want to estimate the percentage of graduates who have made a donation to the college after graduation, how many graduates must you survey if you want 98% confidence that your percentage has a margin of error of
In a Gallup poll, 1011 adults were asked if they consume alcoholic beverages, and 64% of them said that they did. Construct a 90% confidence interval estimate of the proportion of all adults who consume alcoholic beverages. Can we safely conclude that the majority of adults consume alcoholic
Students of the author collected data measuring the accuracy of wristwatches. The times (sec) below show the discrepancy between the real time and the time indicated on the wristwatch. Negative values correspond to watches that are running ahead of the actual time. The data satisfy a loose
Data Set 1 in Appendix B lists the white blood cell counts (1000 cells/µL) of 40 randomly selected women. The mean of those 40 values is 7.15 and the standard deviation is 2.28. Construct a 90% confidence interval estimate of the mean white blood cell count for the population of women. Does the
Data Set 13 in Appendix B includes crash test measurements for small cars. The seven chest deceleration measurements have a mean of 42.7 g and a standard deviation of 5.6 g, where g is a force of gravity. Use the sample data to construct a 95% confidence interval estimate of the mean chest
Refer to the sample data described in Exercise and construct a 95% confidence interval estimate of the population standard deviation.
Find the sample size necessary to estimate the mean number of aggravated assaults on all college campuses so that there is 95% confidence that the sample mean is in error by no more than 2. Assume that a pilot study suggests that the numbers of aggravated assaults at all colleges have a standard
The numbers of aggravated assaults on 40 large urban campuses with residence halls have a mean of 5.5 and a standard deviation of 5.8. Construct a 95% confidence interval estimate of the population mean. In this situation, what is the population?
Data Set 15 in Appendix B includes the times required for flights to taxi out for takeoff. All of the flights are American Airlines flights from New York (JFK) to Los Angeles and they all occurred in January of a recent year. The 48 taxi-out times are depicted in the histogram and normal quantile
In a survey of 1003 people, 59% said that they have never hesitated to give a handshake because they had a fear of germs. The survey results were reported in USA Today, and the survey was conducted by Wakefield Research for Purell, a supplier of hand sanitizer products.a. Construct a 95% confidence
Listed below are HDL and LDL cholesterol measurements (all in mg/dL) from 10 randomly selected women (based on Data Set 1 in Appendix B). Also shown is a scatter plot of the paired data. Based on the scatter plot does there appear to be a correlation between HDL cholesterol levels and LDL
In designing gloves for women, it is found that the lengths of their hands are normally distributed with a mean of 175mm and a standard deviation of 9 mm (based on anthropometric survey data from Gordon, Churchill, et al.). a. What percentage of women have hands longer than 185 mm? If no gloves are
Ohio and several other states have a Pick 3 lottery in which you select three digits, each between 0 and 9. Winning requires that you get the same three digits that are drawn, and they must be in the same order. a. What is the probability of winning a Pick 3 lottery if you buy a single three-digit
A package label includes a claim that the mean weight of the M&Ms is 0.8535 g, and another package label includes the claim that the mean amount of aspirin in Bayer tablets is 325 mg. Which has more serious implications: rejection of the M&M claim or rejection of the aspirin claim? Is it wise to
Tests Data Set 20 in Appendix B includes sample weights of the M&Ms referenced in Exercise. We could use methods of Chapter for making an estimate, or we could use those values to test some claim. What is the difference between estimating and hypothesis testing?
A formal hypothesis test is to be conducted using the claim that the mean body temperature is equal to 98.6°F. a. What is the null hypothesis, and how is it denoted? b. What is the alternative hypothesis, and how is it denoted? c. What are the possible conclusions that can be made about the null
A recent Gallup survey of 1016 randomly selected adults showed that 21% of the respondents smoke. a. Express the original claim in symbolic form. b. Identify the null and alternative hypotheses.
When parents use the XSORT method of gender selection, the proportion of baby girls is greater than 0.5. dhe latest actual results show that among 945 babies born to couples using the XSORT method of gender selection, 879 were girls. a. Express the original claim in symbolic form. b. Identify the
Claim: dhe mean pulse rate (in beats per minute) of adult females is 76 or lower. For the random sample of adult females in Data Set 1 from Appendix B, the mean pulse rate is 77.5. a. Express the original claim in symbolic form. b. Identify the null and alternative hypotheses.

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