Stats final

(Ch 14) A tropical storm is classified as major if... Based on the meteorologist's estimates, approximately what is the probability that a future tropical storm will originate in the Pacific Ocean and be classified as major?

C. 0.153

(Ch 5) For a certain online store, the distribution of number of purchases per hour is approximately normal with mean 1,200 purchases and standard deviation 200 purchases. For what proportion of hours will the number of purchases at the online store exceed 1,400?

E. 16%

(Ch 14) At a California college, 22% of students speak Spanish, 5% speak French, and 3% speak both languages. What is the probability that a student chosen at random from the college speaks French but not Spanish?

A. 0.02

(Ch 5) The commuting time for a student to travel from home to a college campus is normally distributed with a mean of 30 minutes and a standard deviation of 5 minutes. If the student leaves home at 8:25 A.M., what is the probability that the student will arrive at the college campus later than 9 A.M.?

A. 0.16

(Ch 5) Scientists working for a water district measure the water level in a lake each day. The daily water level in the lake varies due to weather conditions and other factors. The daily water level has a distribution that is approximately normal with mean water level of 84.07 feet. the probability that the daily water level in the lake is at least 100 feet is 0.064. Which of the following is closest to the probability that on a randomly selected day the water level in the lake will be at least 90 feet?

A. 0.29

(Ch 13) A friend of yours plans to toss a fair coin 200 times. You watch the first 20 tosses and are surprised that she got 15 heads. But then you get bored and leave. How many heads do you expect her to have when she has finished all 200 tosses?

A. 100

(Ch 5) The distribution of lengths of salmon from a certain river is approximately normal with a standard deviation 3.5 inches. If 10 percent of salmon are stronger than 30 inches, which of the following is closest to the mean of the distribution?

A. 26 inches

(Ch 13) A fair coin has come up 'heads' 10 times in a row. The probability that the coin will come up heads on the next flip is...

A. 50%

(Ch 13) The table shows data that was collected from people who attended a certain high school basketball game and indicates the team each person rooted for and whether each of these people purchases food during the game. A person who attended the game will be selected at random. Which of the following correctly interprets mutually exclusive events represented by the table?

A. Rooting for the home tea, and rooting for the away team.

(Ch 10-12) 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 ne 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 higher 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.

(Ch 14) The SC Electric Company has bid on two electrical writing jobs. The owner of the company believes that - the probability of being awarded the first job (event A) is 0.75; - the probability of being awarded the second job (event B) is 0.5; and - the probability of being awarded both jobs (event (And B)) is 0.375. If the owner's beliefs are correct, which of the following statements must be true concerning event A and event B?

A. even A and event B are not mutually exclusive and are independent.

(Ch 1-4) The distributions of four variables are shown in the following histograms. Which of the following shapes is NOT represented by one of the four distributions?

A. uniform

(Ch 5) A candy company produces individually wrapped candies. the quality control manager for the company believes that the weight of the candies is approximately normally distributed with mean 720 milligrams. If the manager's belief is correct, which of the following intervals of weights will contain the largest proportion of the candies in the distribution of weights?

B. 700mg to 740mg

(Ch 5) The amount of time required for each of 100 mice to navigate through a maze was recorded. The histogram to the right shows the distribution of times, in seconds, for the 100 mice. Which of the following values is closest to the standard deviation of the 100 times?

B. 10 seconds

(Ch 5) The length of life for a battery produced by a machine is normally distributed with a mean of 173 hours and a standard deviation of 5.6 hours. Of the following, which is the best estimate of the percent chance that a battery will last at most 168 hours?

B. 18.6%

(Ch 14) Students at a local elementary school were shown a painting and asked which emotion - joy, happiness, love, or anger- they felt by looking at the painting. the students were classified by their age. The following table summarizes the responses of the students by age-group. One student from the school will be selected at random. What is the probability that the student responded happiness given that the selected student is in the age-group 6 to 8 years old?

B. 20/106

(Ch 5) A distribution of test scores is not symmetric. Which of the following is the best estimate of the z-score of the third quartile?

E. this z-score cannot be estimated from the information given.

(Ch 10-12) At a large conference of teachers from a variety of subjects, a random sample of 50 mathematics teachers attending the conference was selected. Among the selected mathematics teachers, 28 percent had taken one or more courses in statistics. For which of the following populations is 28 percent a reasonable estimate of the percentage of those who have taken one or more courses in statistics?

B. All mathematics teachers who attended the conference

(Ch 1-4) For the three histograms above, which of the following correctly orders the histograms from the one with the smallest proportion of data above its mean to the one with the largest proportion of data above its mean?

B. J, L, K

(Ch 5) When she was attending Memorial Middle School, Mrs. Gray threw shot put and discuss for the track team. Her personal best for shot put and discus events were 24 feet and 52 feet, respectively. When she became a Stats teacher, she discovered that both events are normally distributed. The hot put event can be described by N(22.5 ft, 1.5ft) and the discus event can be described by N(46 ft, 5 ft). Relative to the throws in each respective event, in which event was Mrs. Gray's personal best more impressive?

B. She did better in the discus event

(Ch 13) Which two events are most likely to be independent?

B. registering to vote; being left-handed

(Ch 6-9) At a large airport, data were recorded for one month on how many baggage items were unloaded from each flight upon arrival as well as the time required to deliver all the baggage items on the flight to the baggage claim area. A scatterplot of the two variables indicated a strong, positive linear association between the variables. Which of the following statements is a correct interpretation of the word "strong" in the description of the association?

B. The actual time required to deliver all the items to the baggage claim area based on the number of items unloaded will be very close to the time predicted by a least-squares regression model.

(Ch 6-9) A tennis ball was thrown in the air. The height of the ball from the ground was recorded every millisecond from the time the ball was thrown until it reached the height from which it was thrown. The correlation between the time and height was computed to be0. What does this correlation suggest about the relationship between the time and height?

B. There is no linear relationship between time and height

(Ch 5) Zucchini weights are approximately normally distributed with mean 0.8 pound and standard deviation 0.25 pound. Which of the following shaded regions best represents the probability that a randomly selected zucchini will weigh between 0.55 pound and 1.3 pounds?

C. (It's a graph that has majority of the middle and right side shaded with a sliver of non shaded on the far right).

(Ch 14) The sale bin in a clothing store contains an assortment of t-shirts in different sizes. There are 9 small, 7 medium, and 4 large shirts. Alan is looking for a large shirt. He starts grabbing shirts one at a time and checking the size. After he checks each shirt, he leaves it outside the bin. What is the probability that the first large shirt he finds is the fourth one he checks?

C. 0.116

(Ch 13) A large store has a customer service department where customers can go to ask for help with store-related issues. According to store records, approximately 1/4 of all customers who go to the service department ask for help finding an item. Assume the reason each customer goes to the service department is independent from customer to customer. Based on the approximation, what is the probability that at least 1 of the next 4 customers who go to the service department will ask for help finding an item?

C. 1 - (3/4)^4

(Ch 6-9) The relationship between carbon dioxide emissions and fuel efficiency of a certain car can be modeled by the leas-squares regression equation ln(y)=7-0.045x, where x represents the fuel efficiency, in miles per gallon, and y represents the predicted carbon dioxide emissions, in grams per mile. Which of the following is closest to the predicted carbon dioxide emissions, in grams per mile, for a car of this type with a fuel efficiency of 20 miles per gallon?

C. 446

(Ch 14) Ali surveyed 200 students at a school and recorded the eye color and the gender of each student. Of the 80 male students who were surveyed, 60 had brown eyes. If eye color and gender are independent, how many female students surveyed would be expected to have brown eyes?

C. 90

(Ch 1-4) The pulse rate for each person in a sample pf 20 men and 20 women was recorded. The boxplots below summarize the pulse rates for the men and the women in the sample. Which of the following statements about the people in the sample must be true?

C. At least half of the women had higher pulse rates than three-fourths of the men.

(Ch 6-9) Which of the following statements about a least-squares regression analysis is true? I. A point with a large residual is an outlier II. A point with high leverage has a y-value that is not consistent with the other y-values in the set. III. The removal of an influential point from a data set could change the value of the correlation coefficient.

C. III only

(Ch 10-12) ... As part of the show, a green puppet and a yellow puppet served as a the helper and hinderer. For each baby, a coin was tossed to determine which color would serve which role. Which of the following is the most important reason for the random assignment of color to role in the study?

C. If the same role is played by the same color puppet, the babies might show a preference for the color instead of a preference for the role.

(Ch 14) A high school science teacher has 78 students. Of those students, 35 are in the band and 32 are on a sports team. There are 16 students who are not in the band or on a sports team. One student from the 78 students will be selected at random. Let event B represent the event of selecting a student in the band, and let event S represent the event of selecting a student on a sports team. Are B and S mutually exclusive events?

C. No, because P(B ∩ S) = 5/78

(Ch 10-12) An experiment will be conducted to determine whether children learn their multiplication facts better by practicing with flashcards or by practicing on a computer. Children who volunteer for the experiment will be randomly assigned to one of the two treatments. Because the children's gender may affect the outcome, there will be blocking by gender. After practice, the children will be given a test on the multiplication facts. Why will it be impossible to conduct a double blind experiment?

C. The child will know whether he or she used the flashcards or the computer.

(Ch 1-4) A sociologist collected data from a sample of people on their highest level of education and the number of times they visited any fast food restaurant during the previous week. The data are summarized in the boxplots.

C. The interquartile range (IQR) for the number of visits at the more than four-year college level is less than the IQR for the number of visits at the community college level.

(Ch 10-12) A city planner is investigating traffic congestion at a certain intersection. To collect data, a camera will record the number of cars that pass through the intersection at different hours of the day and on different days of the week. Which of the following best describes the type of investigation being conducted by the city planner?

C. The investigation is an observational study because treatments are not imposed.

(Ch 1-4) 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?

C. The mean is most likely less than the median because the distribution is skewed to the left.

(Ch 1-4) The prices, in thousands of dollars, of 304 homes recently sold in a city are summarized in the histogram below. Based on the histogram, which of the following statements must be true?

C. The median price is not greater than $750,000

(Ch 6-9) A restaurant manager collected data on the number of customers in a party in the restaurant and the time elapsed until the party left the restaurant. The manager computed a correlation of 0.78 between the two variables. What information does the correlation provide about the relationship between the number of customers in a party at the restaurant and the time elapsed until the party left the restaurant?

C. The parties with a larger number of customers are associated with the longer times elapsed until the party left the restaurant.

(Ch 6-9) The height and age of each child in a random sample of children was recorded. The value of the correlation coefficient between height and age for the children in the sample was 0.8. Based on the leas-squares regression line created from the data to predict the height of a child based on the age, which of the following is a correct statement?

C. The proportion of the variation in height that is explained by a regression on age is 64%

(Ch 6-9) A scatterplot of student heights, in inches, versus corresponding arm span length, in inches, is shown below. One of the points in the graph is labeled A. (In the answer choices, LSRL stands for least squares regression line).

C. The slope of the LSRL increases and the correlation coefficient increases

(Ch 10-12) Researches conducted a study to investigate the effects of soft drink consumption on fat stored in muscle tissue. From a sample of 80 adult volunteers, 40 were randomly assigned to consume one liter of a soft drink each day. The remaining 40 were asked to drink one liter of water each day and not to consume any soft drinks. At the end of six months, the amount of fat stored in the tissue than the people who drank only water. Which of the following is the most appropriate conclusion?

C. There is evidence that consuming soft drinks causes more fat storage in muscle tissue than drinking only water, and the conclusion can be generalized to adults similar to those in the study.

(Ch 14) In a certain school, 17 percent of the students are enrolled in a psychology course, 28 percent are enrolled in a foreign language course, and 32 percent are enrolled in either a psychology course or a foreign language course or both. What is the probability that a student chosen at random from this school will be enrolled in both a foreign language course and a psychology course?

D. 0.13

(Ch 13) Of all the fish in a certain river, 20 percent are salmon. Once a year, people can purchase a fishing license that allows them to catch up to 8 fish. Assume each catch is independent. Which of the following represents the probability of needing to catch 8 fish to get the first salmon?

D. 0.2(0.8^7)

(Ch 14) For flights from a particular airport in January, there is a 30 percent chance of a flight being delayed because of icy weather. If a flight is delayed because of icy weather, there is a 10 percent chance the flight will also be delayed because of a mechanical problem. If a flight is not delayed because of icy weather, there is a 5 percent chance that it will be delayed because of a mechanical problem. If one flight is selected at random from the airport in January, what is the probability that the flight selected will have at least one of the two types of delays?

D. 0.335

(Ch 5) A distribution of scores is approximately normal with a mean of 78 and a standard deviation of 8.6. Which of the following equations can be used to find the score x above which 33 percent of the scores fall?

D. 0.44= x-78/8.6

(Ch 13) Opinion-polling organizations contact their respondents by sampling random telephone numbers. Assume that interviewers can now reach about 71% of U.S. households, while the percentage of those contacted who agree to cooperate with the survey is 31%. Each household, it can be safely assumed, is independent of the others. What is the probability of failing to contact a household or of contacting the household but not getting them to agree to he interview?

D. 0.78

(Ch 13) A police officer is using a radar device to check motorists' speeds. prior to beginning the speed check, the officer estimates that 40 percent of motorists will be driving more than 5 miles per hours over the speed limit. Assuming that the police officer's estimate is correct, what is the probability that among 4 randomly selected motorists, the officer will find at least 1 motorist driving more than 5 miles per hour over the speed limit?

D. 0.8704

(Ch 14) Ninety percent of the people who have a particular disease will have a positive result on a given diagnostic test, ninety percent of the people who do not have the disease will have a negative result on this test. If 5 percent of a certain population has the disease, what percent of that population would test negative for the disease?

D. 86%

(Ch 10-12) At a certain clothing store, the clothes are displayed on racks. The clothes on each rack have similar prices, but the prices among the racks are very different. To estimate the typical price of a single piece of clothing, a consumer will randomly select four pieces of clothing from each rack. What type of sample is the consumer selecting?

D. A stratified random sample

(Ch 6-9) Which of the following is the best description of a positive association between two variables?

D. As the value of one of the variables increases, the value of the other variable tends to increase.

(Ch 1-4) Heights, in inches, for the 200 graduating seniors from Washington High School are summarized in the frequency table below. Which of the following statements about the median height is true?

D. It is greater than or equal to 60 inches but less than 66 inches.

(Ch 6-9) A factory has two machines, A and B, making the same part for refrigerators. The number of defective parts produced by each machine during the first hour of operation was recorded on 19 randomly selected days. The scatterplot below shows the number of defective parts produced by each machine on the selected days. Which statement gives the best comparison between the number of defective parts produced by the machines during the first hour of operation on the 19 days?

D. Machine A usually, but not always produced fewer defective parts than machine B.

(Ch 6-9) 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?

D. No, because 3 inches falls above the maximum value of lengths in the sample.

(Ch 10-12) In a recent poll of 1500 randomly selected eligible voters, only 525 (35%) said that they did not vote in the last election. However, a vote count showed that 80% of eligible voters actually did not vote in the last election. Which of the following types of bias is most likely to have occurred in the poll.

D. Response bias

(Ch 6-9) An experiment was conducted to investigate the relationship between the dose of pain medication and the number of hours of pain relief. twenty individual with chronic pain were randomly assigned to one of the five doses - 0.0, 0.5. 1.0, 1.5, 2.0 - in milligrams of medication. The results are shown in the scatterplot below to the right. The data were used to fit a least-squares regression line to predict the number of hours of pain relief for a given dose. Which of the following would be revealed by a plot of the residuals of the regression versus the dose?

D. The variation in the hours of pain relief is not the same across the doses.

(Ch 5) The distribution of the weights of loaves of bread from a certain bakery follows approximately a normal distribution. Based on a very large sample, it was found that 10 percent of the loaves weighed less than 15.34 ounces, and 20 percent of the loaves weighed more than 16.31 ounces. What are the mean and standard deviation of the distribution of the weights of the loaves of bread?

D. μ= 15.93 σ= 0.46

(Ch 13) In a parking lot with 200 cars, 50 cars are white, 30 cars are red, and 20 cars are silver. One car will be selected at random from the parking lot. If each car in the parking lot has only one color, which of the following cannot be the probability that the selected car will be green?

E. 0.6

(Ch 13) At a sporting event, cheerleaders will throw 50 bundled T-shirts into the crowd. the T-shirt sizes consist of 10 small, 15 medium, and the remainder either large or extra large. Suppose Ana catches a T-shirt. What is the probability that she will catch a T-shirt that is not a size small?

E. 0.80

(Ch 13) An experiment was conducted in which planks of wood painted red and green were shown to pigeons to investigate... Based on the results of the simulation, which of the following is closer to the probability that there were at most three successes in a trial?

E. 0.94

(Ch 6-9) Suppose a certain scale is not calibrated correctly, and as a result, the mass of any object is displayed as 0.75 kilogram less than its actual mass. What is the correlation between the actual masses of a set of objects and the respective masses of the same set of objects displayed by the scale?

E. 1

(Ch 1-4) The number of hurricanes reaching the East Coast of the United States was recorded for each of the last ten decades by the National Hurricane Center. Summary measures are shown below. Which of the following statements is true?

E. 24 is an outlier and it is possible that there are other outliers at the high end of the data set. There are no outliers at the low end of the data set.

(Ch 1-4) 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, community college, join the workforce, join the military, or undecided. The results are shown in the following bar chart. Which of the following statements is supported by the bar chart?

E. For the category undecided, the number of students from Liberty High School was 4 greater than the number of students from Central High School.

(Ch 10-12) A local employer asked for help selecting a new type of desk chair. 30 employees volunteered, and each employer used a new desk chair for two weeks and their current desk chair for two weeks. To determine which chair was used first, a coin was flipped for each employee. Heads represented using the new chair first, and tails represented using the current chair first. At the end of each two week period, the employees were asked to rate their satisfaction with the new chair. Which of the following best describes this study?

E. It is a well designed experiment because there is random assignment, replication, and comparison of at least two treatment groups.

(Ch 13) According to a report for veterinarians in the United States, 36.5 percent of households in the United States own dogs and 30.4 percent of households in the United States owns cats. If one household in the United States is selected at random, what is the probability that the selected household will own a dog or a cat.

E. Not enough information is given to determine the probability.

(Ch 14) Events D and E are independent, with P(D) = 0.6 and P(D and E)=0.18. Which of the following is true?

E. P(D or E) = 0.72

(Ch 1-4) A graduate student conducted a study of field mice in rural Kansa. The student obtained a sampled of 100 field mice and recorded the weight, in grams, of each mouse. After the measurements were taken, it was discovered that the scale was not calibrated correctly. The student adjusted the 100 recorded measurements by subtracting 3 grams from each measurement. Which of the following statistics for the weight, in grams, of the field mice has the same value before and after the adjustment?

E. The interquartile range

(Ch 1-4) A graph (not shown) of the selling prices of homes in a certain city for the month of April reveals that the distribution is skewed to the left. Which of the following statements is the most reasonable conclusion about the selling prices based on the graph?

E. The value of maximum minus third quartile is less than the value of first quartile minus minimum.

(Ch 10-12) A researcher wanted to study the effects of a certain chemical on cell growth. The chemical was to be applied at two different doses, high and low, to two different cell types, strain A and strain B. Each combination of dose and cell type was to be replicated ten times. To have consistency from one replicate to the next, the researcher decided to use four lab technicians. One technician would be assigned the high dose with strain A. A second would be assigned the low dose with strain A. A third would be assigned the high dose with strain B. A fourth would be assigned the low dose with strain B. The assignment of lab technician to the replicates for a combination of dose and cell type would be randomized. A statistician told the researcher that the design could be improved by controlling confounding variables. Which of the following is potentially a confounding variable in this study?

B. Lab technician

(Ch 1-4) Which of the following statements must be true about the date sets A and B displayed in the histograms above?

E. The standard deviation of set A is greater than the standard deviation of set B.

(Ch 10-12) A new restaurant is interested in determining the vest time temperature combination for roasting a give pond cut of lamb .The times to be tested are 35 minutes. 60 minutes, and 90 minutes at temperature of 350 degrees Fahrenheit and 425 degrees Fahrenheit for each time, with the exception of the 90 minute - 425 degree combination. That combination is being eliminated because it will overcook the lamb, which leaves five combinations remaining. From 10 identical cuts of lamb, 2 are randomly selected to roast using each of the time-temperature combinations in the same oven. The quality of the finished product is evaluated for each roast. Which of the following is true?

E. The two cuts that are being roasted for each time-temperature combination are an example of replication.