STATS FINAL SEMESTER 1
let the random B represent the number of books a student buys
1.79
A restaurant manager collected data to predict monthly sales for the restaurant from monthly advertising expenses. The model created from the data showed that 36 percent of the variation in monthly sales could be explained by monthly advertising expenses. What was the value of the correlation coefficient? (A) 0.64 (B) 0.60 (C) 0.40 (D) 0.36 (E) 0.13
B) .60
Of the people in the study who had skin cancer, what fraction used a tanning booth? A)190/265 (B) 190/896 C) 190/1436 (D) 265/1, 436 E)896/1436
B) 190/896
A statistician at a metal manufacturing plant is sampling the thickness of metal plates. If an outlier occurs within a particular sample, the statistician must check the configuration of the machine. The distribution of metal thickness has mean 23.5 millimeters (mm) and standard deviation 1.4 mm. Based on the two-standard deviations rule for outliers, of the following, which is the greatest thickness that would require the statistician to check the configuration of the machine? (A) 19.3 mm (B) 20.6 mm (C) 22.1 mm (d)23.5 mm E)24.9 mm
B) 20.6mm
What is indicated by the plot? (A) A linear model is appropriate. (B) A linear model is not appropriate. (C) Variability in y is constant for all values x. (D) At least one point is influential with respect to the regression. (E) At least one point is an outlier with respect to the regression.
B) A linear model is not appropriate
Roger claims that the two statistics most likely to change greatly when an outlier is added to a small data set are the mean and the median. Is Roger's claim correct? (A) Yes, both the mean and median are likely to change greatly. (B) No, only the mean is likely to change greatly. (C) No, only the median is likely to change greatly. (D) No, neither the mean nor the median are likely to change greatly. E) There is not enough information to determine if the mean or the median is likely to change greatly.
B) no, only the mean is likely to change greatly
Which of the following statements is a correct interpretation of the value 19.0 in the output? (A) On average there is a predicted increase of 19.0 ppm in concentration of lead for every increase of 1 ppi in concentration of zinc found in the fish. (B) On average there is a predicted increase of 19.0 ppm in concentration of zinc for every increase of 1 ppm in concentration of lead found in the fish. (C) The predicted concentration of zine is 19.0 ppm in fish with no concentration of lead. (D) The predicted concentration of lead is 19.0 ppm in fish with no concentration of zinc. E) Approximately 19% of the variability in zinc concentration is predicted by its linear relationship with lead concentration.
B) on average there is a predicted increase of 19.0 ppm in concentration of lead for every increase of ppi in concentration of lead found in fish
One statistic calculated for pitchers in baseball is called the camed run average, or ERA. The following boxplots summarize the ERA for pitchers in two leagues, A and B. Based on the boxplots, which of the following statistics is the same for both leagues? A)The range B) The interquartile range C) The median D)The minimum (E)The maximum
B) the interquartile range
One way to measure the duration of subterranean disturbances such as carthquakes and mining is to calculate the root-mean-square time. The following histograms summarize the distributions of the root-mean-square times for two sources of disturbances. Based on the histograms, which of the following correctly compares the two distributions? A)The median of the earthquake disturbances is equal to the median of the mining disturbances. (B) The median of the earthquake disturbances is less than the median of the mining disturbances. C)The range of the carthquake disturbances is equal to the range of the mining disturbances. (D) The range of the carthquake disturbances is less than the range of the mining disturbances. E) The mode of the earthquake disturbances is equal to the mode of the mining disturbances
B) the range of the earthquake disturbances is less than the median of the mining disturbances
A student is applying to two different agencies for scholarships. Based on the student's academic record, the probability that the student will be awarded a scholarship from Agency A is 0.55 and the probability that the student will be awarded a scholarship from Agency B is 0.40. Furthermore, if the student is awarded a scholarship from Agency A, the probability that the student will be awarded a scholarship from Agency B is 0.60. What is the probability that the student will be awarded at least one of the two scholarships? (A) 0.60 (B) 0.62 (C) 0.71 (D) 0.73 (E) 0.95
B).62
For each of the 4 stroke categories, consider a random variable representing the time of a randomly selected swimmer in that category. What is the standard deviation of the sum of the 4 random variables? A)0.83 seconds B)1.67 seconds (C)2.80 seconds D)3.32 seconds (E)3.76 seconds
B)1.67
A certain monthly magazine has both print and online subscribers. Print subscribers are people who pay to have the magazine physically delivered to them each month. Online subscribers are people who pay to have access to the electronic version of the magazine. The editors of the magazine want to study how online subscribers feel about the design of the electronic version, and they will gather data from a sample. Which of the following is a sample of the population of interest? (A) 50 subscribers to the magazine (B)50 print subscribers (C)50 online subscribers (D) 50 people who buy a copy of the magazine at a newsstand (E) 50 people who find an article in the magazine while searching online
C) 50 online subscribers
A market researcher asked a group of men and women to choose their favorite color design from a sample of advertisements. The results are shown in the following fable. Which of the following statements is not supported by the table? (A) More men than women chose the color design red with black. (B) More women than men chose the color design yellow with black. blue. (C)For men, the number who chose a design with black was greater than the number who chose a design with (D) The color design chosen by the most people was green with blue. surveyed by the market researcher.
C) For men, the number who chose a design with black was greater than the number who chose a design with blue
The following histogram shows the ages, in years, of the people who attended a documentary at a movie theater. Based on the histogram, which of the following statements best describes the relationship between the mean and the median of the distribution of ages? (A) The mean and the median are equal in value because the distribution is symmetric. The mean is most likely less than the median because the distribution is skewed to the right. (C) The mean is most likely less than the median because the distribution is skewed to the left. (D) The mean is most likely greater than the median because the distribution is skewed to the right. (E)The mean is most likely greater than the median because the distribution is skewed to the left.
C) The mean is most likely less than the median because the distribution is skewed to the left
Which of the following statements is supported by the bar chart? (A) The proportion of holes created for drumming is the same for all three siding types. (B) The proportion of holes created for drumming is greatest for grooved plywood. (C) The proportion of holes created for drumming is least for grooved plywood. (D) The number of holes created for drumming is least for grooved plywood. E) The number of holes created for drumming is greatest for nonwood.
C) the proportion of hole created for drumming is least for grooved plywood
A certain county school district has 15 high schools. The high school seniors' plans after graduation in each school vary greatly from one school to the next. The county superintendent will select a sample of high school seniors from the district to survey about their plans after graduation. The superintendent will use a cluster sample with the high schools as clusters. A random sample of 5 high schools will be selected, and all seniors at those high schools will complete the survey. What is one disadvantage to selecting a cluster sample to investigate the superintendent's goal? (A) Cluster sampling is usually very expensive to implement and could cost the district too much money. B) Because every senior in the selected clusters will complete the survey, the sample will be too large to yield accurate results. C) The schools in the cluster sample might not be representative of the population of seniors. D) There could
C) the schools in the cluster sample might not be representative of the population of seniors
One student from a high school will be selected at random. Let A be the event that the selected student is a student athlete, and let B be the event that the selected student drives to school. If P(An B) = 0.08 and P(B|A) = 0.25, what is the probability that the selected student will be a student athlete? A).2 B).17 C).32 D).33 E)3.13
C).32
Data were collected on the ages, in years, of the men and women enrolled in a large sociology course. Let the random variables M and W represent the ages of the men and women, respectively. The distribution of M has mean 20.7 years and standard deviation 1.73 years. The distribution of W has mean 20.2 years and standard deviation 1.60 years. Of all of those enrolled in the course, 54 percent are men and 46 percent are women. What is the mean age of the combined distribution of both men and women in the course? (A) 20.2 years (B) 20.43 years (C)20.45 years (D) 20.47 years (E)40.9 years
D) 20.47
In a certain school district, students from grade 6 through grade 12 can participate in a school-sponsored community service activity. The following bar chart shows the relative frequencies of students from each grade who participate in the community service activity. Which of the following statements is supported by the bar chart? A)The greatest number of participating students was in grade 9. B) The number of participating students in grade 6 was equal to the number of participating students in grade 7. C) The relative frequency of all participating students in grades 6 and 7 combined was 0.60. D) Grade 12 had the least relative frequency of participating students. E) Grade 11 had the greatest relative frequency of participating students.
D) Grade 12 had the least relative frequency of participating students
For a specific species of fish in a pond, a wildlife biologist wants to build a regression equation to predict the weight of a fish based on its length. The biologist collects a random sample of this species of fish and finds that the lengths vary from 0.75 to 1.35 inches. The biologist uses the data from the sample to create a single linear regression model. Would it be appropriate to use this model to predict the weight of a fish of this species that is 3 inches long? (A) Yes, because 3 inches falls above the maximum value of lengths in the sample. (B) Yes, because the regression equation is based on a random sample. (C) Yes, because the association between length and weight is positive. (D) No, because 3 inches falls above the maximum value of lengths in the sample. (E) No, because there may not be any 3-inch fish of this species in the pond.
D) No because 3 inches falls below the maximum value of lengths in the sample
The following boxplot summarizes the heights of a sample of 100 trees growing on a tree farm. Emily claims that a tree height of 43 inches is an outlier for the distribution. Based on the 1.5 x IQR rule for outliers, is there evidence to support the claim? (A) Yes, because (max - Q3) is greater than (Q,1 - min). (B) Yes, because 43 is greater than (Q3 + IQR.). (C) Yes, because 43 is greater than (Q1 - 1.5 x IQR). (D) No, because 43 is not greater than (Q3 + 1.5 x IQR). (E) No, because 43 is greater than (Q1 - 1.5 x IQR).
D) No, because 43 is not greater than (Q3+1.5 xIQR)
The following list shows the number of video games sold at a game store each day for one week. 15, 43, 50, 39, 22, 16, 20 Which of the following is the best classification of the data in the list? (A) Categorical and continuous Quantitative and continuous Categorical and discrete (D) Quantitative and discrete (E) Neither categorical nor quantitative, and neither discrete nor continuous
D) Quantitative and discrete
An observational study found that the amount of sleep an employee gets each night is associated with job performance. The correlation coefficient was found to be r = 0.86. A reader of the study concluded that more sleep causes employees to perform better. Why is such a conclusion not correct? (A) The correlation value should equal 1 for such a conclusion. (B) The correlation value should be negative for such a conclusion. ©C)The sample was not representative of the population. (D) Causation cannot be determined from an observational study. E)The correlation value implies that less than 75% of the variability in job performance can be explained by sleep.
D) causation cannot be determined from an observation study
81 percent of adults in a certain state have graduated from highschool
(15 5) (.19)
According to a recent survey 31 percent of the residents of a certain state who are age 25
(50,40) (.31)
o fall the fish in a certain river
.2 (.8)
A middle school chess club has 5 members
1/10
At a small coffee shop. the distribution of the number of seconds it takes for a cashier to process an order is approximately normal with mean 276 seconds and standard deviation 38 seconds. Which of the following is closest to the proportion of orders that are processed in less than 240 seconds? A）） 0.17 b. 0.25 c. 0.36 d. .83 (E) 0.95
A) .17
A school nutritionist was interested in how students at a certain school would feel after taking a nutritional supplement. The nutritionist selected a random sample of twenty students from the school to participate in the study. Participants were asked to keep a journal on how well they felt after taking the supplement each day. What possible source of bias is present in the method of data collection? (A) Bias from a sampling method that only uses volunteers (B) Undercoverage bias (C) Nonresponse bias (D) Response bias where responses are self-reported E)Response bias where the question wording is leading or confusing
D)response bias when responses are self reported
a store owner reports that the probability that a customer who purchases a lawn mower will also purchase an extended warranty is .68
for all customers who purchase a lawn mower, 68%will also purchase an extended warranty
A highschool teacher has 78 students,
no because 5/78
A market research firm is studying the effects of price and type of packaging on sales of a particular product. Twenty-seven stores with shoppers of similar characteristics will be used in the study. The nine combinations of three price levels and three packaging types are the treatments of interest. Total sales of the product over a seven-week period will be recorded. Which of the following describes the best design to use for the study? A completely randomized design. Randomly assign the nine combinations of price level and packaging type so that three stores use each combination. B)A completely randomized design. Randomly assign the three price levels so that nine stores use each price level. C)A completely randomized design. Randomly assign the three packaging types so that nine stores use each type of packaging. (D) A randomized block design. Use packaging as a block. Randomly assign the nine combinations of thr
A) A completely randomized design. Randomly assigned the nine combinations of price level and packaging type so that three stores use each combination
A store owner reports that the probability that a customer who purchases a lawn mower will also purchase an extended warranty is 0.68. Which of the following is the best interpretation of the probability 0.68? (A) For all customers who purchase a lawn mower, 68% will also purchase an extended warranty. For all customers of the store, 68% will purchase a lawn mower. (C) For all customers who purchase an extended warranty, 68% will use the warranty. (D) From the next 25 customers, 17 will purchase an extended warranty. (E) From the next 25 customers, 17 will purchase a lawn mower.
A) For all customers who purchase a lawn mower, 68% will also purchase an extended warranty
A field researcher who studies lions conjectured that the more time a cub spends playing, the sooner the cub will begin to bunt. Observational data were collected from 20 lion cubs. The researcher recorded how long they spent playing and the age when they began hunting. Because male and female lions have different hunting behaviors, the researcher recorded the data for males and females separately. The two scatterplots show the data for the 10 female lions and the 10 male lions. Based on the scatter plots, for which gender does there appear to be evidence that the more time a lion cub spends playing, the sooner the cub is likely to begin hunting? (A) For female cubs only (B) For male cubs only (C) For both male cubs and female cubs, with equal evidence (D) For both male cubs and female cubs, with more evidence for female cubs than for male cubs (E) For neither male
A) For female cubs only
A chemist for a paint company conducted an experiment to investigate whether a new outdoor paint will last longer than the older paint. Fifty blocks made from the same wood were randomly assigned to be painted with either the new paint or the old paint. The blocks were placed into a weather-controlled room that simulated extreme weather conditions such as ice, temperature, wind, and sleet. After one month in the room, the blocks were removed, and each block was rated on texture, shine, brightness of color, and chipping. The results showed that the blocks painted with the new paint generally had bigher ratings than the blocks painted with the old paint. However, an analysis of the results found that the difference in ratings was not statistically significant. What can be concluded from the experiment? (A) There is not enough evidence to attribute the higher ratings to the new paint. (B) The new paint will last longer
A) There is no enough evidence to attribute the higher rating to the new paint
At a photography contest, entries are scored on a scale from 1 to 100. At a recent contest with 1.000 entries, a score of 68 was at the 77th percentile of the distribution of all the scores. Which of the following is the best description of the 77th percentile of the distribution? (A) There were 770 entries with a score less than or equal to 68. (B) There were at least 230 entries with a score of 77. (C) There were 23% of the entries with a score less than or equal to 68. D) There were 77% of the entries with a score equal to 68. E) There were at least 77% of the entries with a score greater than 68.
A) There were 770 entries with a score less than or equal to 68
Which of the following is the best description of the relationship displayed in the scatterplot? (A) Negative, linear, and strong (B) Positive, linear, and weak (C) Negative, nonlinear, and strong (D) Positive, nonlinear, and weak (E) Positive, nonlinear, and strong
A) negative, linear, and strong
A city has designed a survey to collect information about residents' opinions about city services. Which of the collowing describes a scenario in which nonresponse bias is likely present? (A) Surveys were mailed to 500 people, and 200 of the surveys were completed and returned. (B) Surveys were mailed to one-half of the neighborhoods in the city and all surveys were returned C) Surveys were completed by the first 500 residents who listened to a radio show (D) Surveys were completed by 500 residents selected at random E) Surveys were given to all residents in one neighborhood of the city and all surveys were retumed
A) surveys were mailed to 500 people and 200 of the surveys were completed and returned
The quality-control manager of a large factory is concerned about the number of defective items produced by workers. Thirty workers at the factory agree to participate in a study of three different incentive plans to help reduce the number of defective items produced. The plans will be randomly assigned to the workers so that 10 workers received each plan. The reduction in the number of defective items produced by each worker will be recorded two weeks after the plans are implemented. Which of the following best describes why a completely randomized design is an appropriate design to use in this situation? (A) There is no blocking variable, and incentive plans will be randomly assigned to the workers. (B) There is no blocking variable, and the workers were selected at random. (C) Each incentive plan is a block, and a completely randomized design is not blocked. (D) Each plan will be randomly assigned to 10 pairs of w
A) there is no blocking variable and incentive plans will be randomly assigned to the workers
Suppose a roadrunner has a total length of 59.0 cm and tail length of 31.1 cm. Based on the residual, does the regression model overestimate or underestimate the tail length of the roadrunner? (A) Underestimate, because the residual is positive. (B) Underestimate, because the residual is negative. (C) Overestimate, because the residual is positive. (D) Overestimate, because the residual is negative. (E) Neither, because the residual is 0.
A) underestimate, because the residual is positive
The owner of a food store conducted a study to investigate whether displaying organic fruit at the front of the store rather than at the back of the store will increase sales of the fruit. At the beginning of each week. the organic fruit display was randomly assigned to either the front or the back of the store, and sales for the week were recorded. At the end of 12 months, the owner determined that the average weekly sales of organic fruit displayed at the front of the store were greater than the average weekly sales of organic fruit displayed at the back of the store. The difference was statistically significant. What can be concluded froin the study? (A) Sales of organic fruit generally increased over the 12-month period. (B) Shoppers will buy more organic fruit each day if they see it when they first enter the store. (C) Any conclusion is problematic because the different types of fruit were not taken into accoun
D) placing the display at the front instead of the back of the store causes an increase, on average, of weekly sales of the organic fruit
To estimate the percent of red marbles in a large bag of marbles, Margo will use the following sampling method. She will randomly select a marble, record its color, put it back into the bag, shake the bag to thoroughly mix the marbles, and then repeat those steps. She will perform the procedure many times. What type of sampling method is Margo using? (A) Cluster sampling (B) Stratified random sampling (C) Systematic random sampling D)Random sampling with replacement (E)Random sampling without replacement
D) random assignment with replacement
The random variable X has mean 12 and standard deviation 3. The random variable W is defined as W = 7+ 2X. What are the mean and standard deviation of W? (A) The mean is 24, and the standard deviation is 6 (B) The mean is 24, and the standard deviation is 13 (C) The mean is 31, and the standard deviation is 3. (D) The mean is 31, and the standard deviation is 6. (E) The mean is 31, and the standard deviation is 13.
D) the mean is 31 and the standard deviation is 6
For a random sample of 20 professional athletes, there is a strong, linear relationship between the number of hours they exercise per week and their resting heart rate. For the athletes in the sample, those who exercise more hours per week tend to have lower resting heart rates than those who exercise less. Which of the following is a reasonable value for the correlation between the number of hours athletes exercise per week and their resting heart rate? (A) 0.71 (B) 0.00 C) -0.14 (D) -0.87 E) -1.00
D)-.87
The least-squares regression line y = 1.8 - 0.2x summarizes the relationship between velocity, in feet per second, and depth, in feet, in measurements taken for a certain river, where ge represents velocity and y represents the depth of the river. What is the predicted value of y, in feet, when x = 5? A)-16 B)-1 C)-.2 D).8 E)1.8
D).8
The following boxplot shows the typical gas milcage, in miles per gallon, for 20 different car models. Based on the boxplot, the top 25 percent of the cars have a typical gas mileage of at least how many miles per gallon? (A) 15 (B) 20 (C) 25 (D) 35 (E) 50
D)35
A researcher is studying the effect of genetically modified (GM) and nongenetically modified (nGM) com on the weight gain of lambs. The sex and genetics of the lambs can affect their weight gain. Five sets of male twin lambs and five sets of female twin lambs —for a total of twenty lambs-are available for the study. The lambs will be randomly assigned to a diet of either GM or nGM diet of corn. Weight gain will be recorded for each lamb after five weeks on the diet. Which of the following designs would be best to use in the study? (A) A completely randomized design. Randomly assign ten lambs to the GM diet and ten lambs to the nGM (B)A stratified randomized design. Divide the lambs into males and females. Within each group, randomly assign the GM diet to one half and the nGM diet to the other half. C) A randomized block design. Randomly assign ten lambs to the GM diet and ten lambs to the nGM diet. D)A randomized b
E) A matched pairs design. For each set of twins, randomly assign one twin to the GM diet and the other twin to the nGM diet
A researcher selects a simple random sample of 1,200 women who are students at Midwestern colleges in the United States to use for an observational study. Which of the following describes the population to which it would be most reasonable to generalize the results? (A) All students in the United States (B) All college students in the United States (C) All women who are students in the United States (D) All students at Midwestern colleges in the United States (E) All women who are students at Midwestern colleges in the United States
E) All women who are students at midwestern colleges in the UNited States
A sample of 100 students from Liberty High School and a sample of 60 students from Central High School were asked what they planned to do after graduation. Responses fell into five categories: four-year university (4Y), community college (CC). join the workforce (W), join the military (M), or undecided (UD). The results are shown in the following bar chart. Which of the following statements is supported by the bar chart? For the category four-year university. the number of students from Central High School was 10 greater than (A)the number of students from Liberty High School. (B) At Liberty High School, more students selected a four-year university than any other activity. (C) For the category join the workforce, the number of students from each school was equal. (D) At Central High School, the same number of students selected four-year university and military. E) For the category undecided, the number of students f
E) For the category undecided, the number of students from liberty school was 4 greater than the number of students from central high school
The probability that a randomly selected visitor to a certain website will be asked to participate in an online survey is 0.40. Avery claims that for the next 5 visitors to the site, 2 will be asked to participate in the survey. Is Avery interpreting the probability correctly? (A) Yes, because 2 out of 5 is equal to 40%. (B) Yes, because participants in the survey are selected at random. (C) No, because there could be voluntary response bias. (D) No, because only 40% of all people will visit the site. (E) No. because 0.40 represents probability in the long run over many visits to the site.
E) no, because .40 represents probability in the long run over many visits to the site
Eighteen individuals who use a particular form of social media were assigned a new user interface to use when logging in to their accounts. After using the new user interface for a week, each individual was asked to rate how easy or hard the new user interface was to use on a scale from I (extremely easy) to 9 (extremely hard). Which of the following correctly identifies why this is not a well-designed experiment? (A) There was a lack of control because not all individuals in the study used login passwords of the same length. (B) The individuals may not have been randomly selected. (C) There was not enough replication because the individuals used the new user interface for only one week. (D) There was a lack of control because not all individuals in the study use social media. （E） The study was not comparative-only one treatment was used.
E) the study was not comparative- only one treatment was used
