Find the indicated probability using the standard normal distribution. If convenient, use technology to find the probability. P(z < 1.28)
> Does the day a house is listed for sale affect how long it takes for the sale to be completed or its selling price? A study conducted by economists attempted to answer the question. A random sample of houses that sold in a major city was studied. The num
> Refer to Exercise 14.129. A similar study determined the monthly household income of households headed by 25- to 34-year-olds with only a high school diploma. The incomes were converted to 2012 dollars. a. Is there sufficient evidence to infer that house
> In an election held last year that was contested by three parties. Party A captured 31% of the vote, party B garnered 51%, and party C received the remaining votes. A survey of 1,200 voters asked each to identify the party that they would vote for in the
> Refer to Exercise 14.129. A similar study was conducted for Bachelor’s degrees. a. Can we infer from the data that incomes differed for 25- to 34-year-olds with Bachelor’s degrees between the three periods? b. Are the required conditions satisfied? Expla
> How have 25- to 34-year-olds with university degrees fared financially since 1984? To answer this question, the Pew Research Center conducted surveys in 1984, 1996, and 2009 recording monthly earnings for graduates with three different types of degrees.
> A random sample of 500 teenagers were grouped in the following way: ages 13–14, 15–17, and 18–19. Each teenager was asked to record the number of Facebook friends each had. Is there sufficient evidence to infer that there are differences in the number of
> Millions of North Americans spend up to several hours a day commuting to and from work. Other than the wasted time, are there other negative effects associated with fighting traffic? A study by Statistics Canada may shed light on the issue. A random samp
> Stock market investors are always seeking the “Holy Grail,” a sign that tells them the market has bottomed out or achieved its highest level. There are several indicators. One is the buy signal developed by Gerald Appel, who believed that a bottom has be
> When the stock market has a large 1-day decline, does it bounce back the next day or does the bad news endure? To answer this question, an economist examined a random sample of daily changes to the Toronto Stock Index (TSE). He recorded the percent chang
> Virtually all restaurants attempt to have three “seatings” on weekend nights. Three seatings means that each table gets three different sets of customers. Obviously, any group that lingers over dessert and coffee may result in the loss of one seating and
> Studies indicate that single male investors tend to take the most risk, whereas married female investors tend to be conservative. This raises the question, which does best? The risk-adjusted returns for single and married men, and for single and married
> Increasing tuition has resulted in some students being saddled with large debts on graduation. To examine this issue, a random sample of recent graduates was asked to report whether they had student loans, and if so, how much was the debt at graduation.
> Are babies who are exposed to music before their birth smarter than those who are not? And, if so, what kind of music is best? Researchers at the University of Wisconsin conducted an experiment with rats. The researchers selected a random sample of pregn
> License records in a county reveal that 15% of cars are subcompacts (1), 25% are compacts (2), 40% are midsize (3), and the rest are an assortment of other styles and models (4). A random sample of accidents involving cars licensed in the county was
> Many of you reading this page probably learned how to read using the whole-language method. This strategy maintains that the natural and effective way is to be exposed to whole words in context. Students learn how to read by recognizing words they have s
> It is important for salespeople to be knowledgeable about how people shop for certain products. Suppose that a new car salesman believes that the age and gender of a car shopper affect the way he or she makes an offer on a car. He records the initial off
> On reconsidering the experiment in Exercise 14.117, the psychologist decides that the age of the child may influence the attention span. Consequently, the experiment is redone in the following way. Three 10-year-olds, three 9-year-olds, three 8-year-olds
> In marketing children’s products, it is extremely important to produce television commercials that hold the attention of the children who view them. A psychologist hired by a marketing research firm wants to determine whether differences in attention spa
> The editor of the student newspaper was in the process of making some major changes in the newspaper’s layout. He was also contemplating changing the typeface of the print used. To help himself make a decision, he set up an experiment in which 20 individ
> The possible imposition of a residential property tax has been a sensitive political issue in a large city that consists of five boroughs. Currently, property tax is based on an assessment system that dates back to 1950. This system has produced numerous
> To help high school students pick a major, a company called PayScale surveys graduates of a variety of programs. In one such survey, graduates of the following degree programs were asked what their annual salaries were after working at least 10 years in
> Each year billions of dollars are lost because of worker injuries on the job. Costs can be decreased if injured workers can be rehabilitated quickly. As part of an analysis of the amount of time taken for workers to return to work, a sample of male blue-
> The marketing department of a firm that manufactures office furniture has ascertained that there is a growing market for a specialized desk that houses the various parts of a computer system. The operations manager is summoned to put together a plan that
> Refer to Example 12.6. In segmenting the breakfast cereal market, a food manufacturer uses health and diet consciousness as the segmentation variable. Four segments are developed: 1. Concerned about eating healthy foods 2. Concerned primarily about weigh
> Financial managers are interested in the speed with which customers who make purchases on credit pay their bills. In addition to calculating the average number of days that unpaid bills (called accounts receivable) remain outstanding, they often prepare
> Refer to Exercise 12.132. The women in the survey were also asked to define value by identifying what they considered to be the most important attribute of value. The responses are: 1. Price 2. Quality 3. Fashion The responses and the classifications of
> Exercise 12.132 described the market segments defined by JC Penney. Another question included in the questionnaire that classified the women surveyed was asked whether each worked outside the home. The responses were: 1. No 2. Part-time job 3. Full-time
> Exercise 2.64 described the survey the Red Lobster Restaurant chain conducts to monitor the performance of individual restaurants. One of the questions asks customers to rate the overall quality of their last visit. The listed responses are Poor (1), Fai
> Exercises 2.33 and 2.49 described a survey that took a random sample of 285 graduating students and asked each to report which of the following is their favorite light beer: 1 =Bud Light, 2 = Busch Light, 3 = Coors Light, 4 = Michelob Light, 5 = Miller L
> Exercise 2.46 asked the question: Are you more likely to smoke if your parents smoke? To shed light on the issue, a sample of 20- to 40-yearold people was asked whether they smoked and whether their parents smoked. The results are stored the following wa
> Exercise 2.65 described a survey of the business school graduates undertaken by a university placement office. The respondents reported (among other questions) gender (1 = Female, 2 = Male) and area of employment (1= Accounting, 2 = Finance, 3 = General
> Example 12.5 described exit polls wherein people are asked whether they voted for the Democrat or Republican candidate for president. The surveyors also record gender (1 = Female, 2 = Male), educational attainment (1 = Did not finish high school, 2 = Com
> Exercise 13.164 described a survey of adults wherein, on the basis of several probing questions, each was classified as either a memberof the health conscious group (code = 1) or not (code = 2) and whether he or she buys Special X (1 = No, 2 = Yes). Addi
> Exercise 12.111 described a study to determine whether viewers (older than 50) of the network news had contacted their physician to ask about one of the prescription drugs advertised during the newscast. The responses (1 = No, 2 = Yes) were recorded. Als
> Refer to Exercise 12.110. Determine whether there is enough evidence to infer thatthere are differences in the choice of Christmas tree between the three age categories. Data from Exercise 12.110: An important decision faces Christmas holiday celebrator
> Pat Statsdud is about to write a multiple- choice exam but as usual knows absolutely nothing. Pat plans to guess one of the five choices. Pat has been given one of the professor’s previous exams with the correct answers marked. The correct choices were r
> Repeat Exercise 15.1 with the following frequencies: Cell 1 2 3 4 5 Frequency 6 16 21 18 14 Data from Exercise 15.1: Consider a multinomial experiment involving n = 300 trials and k = 5 cells. The observed frequencies resulting from the e
> The random variable x is normally distributed with mean µ = 74 and standard deviation σ = 8. Find the indicated probability. P(72 < x < 82)
> The random variable x is normally distributed with mean µ = 74 and standard deviation σ = 8. Find the indicated probability. P(60 < x < 70)
> The random variable x is normally distributed with mean µ = 74 and standard deviation σ = 8. Find the indicated probability. P(x > 71.6)
> The random variable x is normally distributed with mean µ = 74 and standard deviation σ = 8. Find the indicated probability. P(x > 80)
> The random variable x is normally distributed with mean µ = 74 and standard deviation σ = 8. Find the indicated probability. P(x < 55)
> The random variable x is normally distributed with mean µ = 74 and standard deviation σ = 8. Find the indicated probability. P(x < 84)
> Find the indicated probability using the standard normal distribution. If convenient, use technology to find the probability. P(z < 0 or z > 1.68)
> Find the indicated probability using the standard normal distribution. If convenient, use technology to find the probability. P(z < -2.50 or z > 2.50)
> Find the indicated probability using the standard normal distribution. If convenient, use technology to find the probability. P(0.42 < z < 3.15)
> Find the indicated probability using the standard normal distribution. If convenient, use technology to find the probability. P(-2.15 < z < 1.55)
> Find the expected net gain to the player for one play of the game. It costs $25 to bet on a horse race. The horse has a 1/8 chance of winning and a 1/4 chance of placing 2nd or 3rd. You win $125 if the horse wins and receive your money back if the horse
> Find the indicated probability using the standard normal distribution. If convenient, use technology to find the probability. P(z > -0.74)
> The scores for the reading portion of the ACT test are normally distributed. In a recent year, the mean test score was 21.3 and the standard deviation was 6.5. The test scores of four students selected at random are 17, 29, 8, and 23. Determine whether a
> The scores for the reading portion of the ACT test are normally distributed. In a recent year, the mean test score was 21.3 and the standard deviation was 6.5. The test scores of four students selected at random are 17, 29, 8, and 23. Find the z-score th
> Find the indicated area under the standard normal curve. If convenient, use technology to find the area. To the left of z = 0.64 and to the right of z = 3.415
> Find the indicated area under the standard normal curve. If convenient, use technology to find the area. To the left of z = -1.5 and to the right of z = 1.5
> Find the indicated area under the standard normal curve. If convenient, use technology to find the area. Between z = -2.68 and z = 2.68
> Find the indicated area under the standard normal curve. If convenient, use technology to find the area. Between z = 0.05 and z = 1.71
> Find the indicated area under the standard normal curve. If convenient, use technology to find the area. Between z = -1.55 and z = 1.04
> Find the indicated area under the standard normal curve. If convenient, use technology to find the area. Between z = -1.64 and z = 0
> a. find the mean, variance, and standard deviation of the probability distribution, and b. interpret the results. A television station sells advertising in 15-, 30-, 60-, 90-, and 120-second blocks. The distribution of sales for
> Find the indicated area under the standard normal curve. If convenient, use technology to find the area. To the right of z = 0.015
> Find the indicated area under the standard normal curve. If convenient, use technology to find the area. To the left of z = -2.825
> Find the indicated area under the standard normal curve. If convenient, use technology to find the area. To the right of z = 3.22
> Find the indicated area under the standard normal curve. If convenient, use technology to find the area. To the right of z = -0.57
> Find the indicated area under the standard normal curve. If convenient, use technology to find the area. To the left of z = -1.95
> Find the indicated area under the standard normal curve. If convenient, use technology to find the area. To the left of z = 0.33
> Five adults who participated in the survey in Example 5 are randomly selected and asked whether they use the social media platform Instagram. Construct a binomial distribution for the number of adults who respond yes.
> A card is selected from a standard deck and replaced. This experiment is repeated a total of five times. Find the probability of selecting exactly three clubs.
> Find the area of the indicated region under the standard normal curve. If convenient, use technology to find the area. -2.35 -0.8 0
> Determine whether the experiment is a binomial experiment. If it is, specify the values of n, p, and q, and list the possible values of the random variable x. If it is not, explain why. You take a multiple-choice quiz that consists of 10 questions. Each
> In San Francisco, California, about 44% of the days in a year are clear. Find the mean, variance, and standard deviation for the number of clear days during the month of May. Interpret the results and determine any unusual events.
> At a raffle, 2000 tickets are sold at $5 each for five prizes of $2000, $1000, $500, $250, and $100. You buy one ticket. Find the expected value and interpret its meaning.
> Find the variance and standard deviation of the probability distribution constructed in Try It Yourself 2.
> Find the mean of the probability distribution you constructed in Try It Yourself 2. What can you conclude?
> Determine whether each distribution is a probability distribution. Explain your reasoning. 1. 2. 5 6 7 8 1 2 3 4. P(x) P(x) 0.09 0.36 0.49 0.10 16 4
> Verify that the distribution you constructed in Try It Yourself 2 is a probability distribution. From Try It Yourself 2: P(x) 0.16 0.19 0.15 16 1 19 2 15 3 21 0.21 4 9 0.09 5 10 0.10 8 0.08 2 n = 100 7 0.02 EP(x) =1
> A company tracks the number of sales new employees make each day during a 100-day probationary period. The results for one new employee are shown at the left. Construct a probability distribution for the random variable x. Then graph the distribution usi
> Determine whether each random variable x is discrete or continuous. Explain your reasoning. 1. Let x represent the speed of a rocket. 2. Let x represent the number of calves born on a farm in one year. 3. Let x represent the number of days of rain for
> Construct the 90% and 95% confidence intervals for the population variance and standard deviation of the medicine weights.
> Find the area of the indicated region under the standard normal curve. If convenient, use technology to find the area. 0 0.46
> Find the critical values x2R and x2L for a 90% confidence interval when the sample size is 30.
> A researcher is estimating the population proportion of people in the United States who delayed seeking medical care during the last 12 months due to costs. The estimate must be accurate within 2% of the population proportion with 90% confidence. Find th
> Use the data in Example 3 to construct a 99% confidence interval for the population proportion of 18- to 29-year-olds who get their news online. From Example 3: NEWS Percent of 18- to 29-year-olds who get news on each platform Online 50% Television
> Use the data in Try It Yourself 1 to construct a 90% confidence interval for the population proportion of U.S. adults who shop online at least once a week. From Try It Yourself 1: How often do you shop online? At least once a week Number responding
> A poll surveyed 4780 U.S. adults about how often they shop online. The results are shown in the table. Find a point estimate for the population proportion of U.S. adults who shop online at least once a week. How often do you shop online? At least onc
> You randomly select 18 adult male athletes and measure the resting heart rate of each. The sample mean heart rate is 64 beats per minute, with a sample standard deviation of 2.5 beats per minute. Assuming the heart rates are normally distributed, should
> Construct 90% and 95% confidence intervals for the population mean number of days the car model sits on the dealership’s lot in Example 3. Compare the widths of the confidence intervals.
> Construct 90% and 99% confidence intervals for the population mean temperature of coffee sold in Example 2.
> Find the critical value tc for a 90% confidence level when the sample size is 22.
> In Example 6, how many student-athletes must the researcher include in the sample to be 95% confident that the sample mean is within 0.75 hour of the population mean? Compare your answer with Example 6.
> Use the normal curves shown. Which normal curve has the greatest standard deviation? Explain your reasoning. B 80 90 100 110 120 130 140
> Construct a 90% confidence interval for the population mean age for the college students in Example 5 with the sample size increased to 30 students. Compare your answer with Example 5.
> Use the data in Example 1 and technology to construct 75%, 85%, and 90% confidence intervals for the mean number of hours spent on required athletic activities by all student-athletes in the conference. How does the width of the confidence interval chang
> Use the data in Try It Yourself 1 to construct a 95% confidence interval for the mean number of hours spent on required athletic activities by all student-athletes in the conference. Compare your result with the interval found in Example 3. From Try It
> Use the data in Try It Yourself 1 and a 95% confidence level to find the margin of error for the mean number of hours spent on required athletic activities by all student-athletes in the conference. Assume the population standard deviation is 2.3 hours.
> In Example 1, the researcher selects a second random sample of 30 student-athletes and records their numbers of hours spent on required athletic activities (see table at left). Use this sample to find another point estimate of the population mean m.
> The study in Example 5 found that 32.0% of all men in the United States ages 50 and older have arthritis. You randomly select 75 men in the United States who are at least 50 years old and ask them whether they have arthritis. What is the probability that
> In Example 4, what is the probability that at most 80 drivers will say yes, they have yelled at another driver?
> In a survey of adults in the United States, 29% said they have seen a person using a mobile device walk in front of a moving vehicle without looking. You randomly select 100 adults in the United States and ask them whether they have seen a person using a
> Use a continuity correction to convert each binomial probability to a normal distribution probability. 1. The probability of getting between 57 and 83 successes, inclusive 2. The probability of getting at most 54 successes
> A binomial experiment is listed. Determine whether you can use a normal distribution to approximate the distribution of x, the number of people who reply yes. If you can, find the mean and standard deviation. If you cannot, explain why. In a survey of a
> Determine whether you can use a normal distribution to approximate the binomial distribution. If you can, use the normal distribution to approximate the indicated probabilities and sketch their graphs. If you cannot, explain why and use a binomial distri
