AP Stats Midterm
Are BB and SS mutually exclusive events? A No, because P(B∩S)=578P(B∩S)=5/78. B No, because P(B∩S)=4878P(B∩S)=48/78. C No, because P(B∩S)=6278P(B∩S)=62/78. D Yes, because P(B∩S)=578P(B∩S)=5/78. E Yes, because P(B∩S)=6278P(B∩S)=62/78.
A
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 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 three price levels and three packaging types so that three stores use each combination. E A randomized block design. Use packaging as a block. Randomly assign nine stores to each packaging type, then randomly assign price level to three stores within each block.
A
Let the random variable Q represent the number of students who go to a certain teacher's office hour each day. The standard deviation of Q is 2.2. Which of the following is the best interpretation of the standard deviation? A On average, the number of students going to an office hour varies from the mean by about 2.2 students. B For a randomly selected office hour, the number of students who will go is 2.2. C For a randomly selected office hour, the number of students expected to go will vary from the mean by 2.2 students. D For a random selection of office hours, the average number of students expected to go is 2.2. E For a random selection of office hours, the average number of students expected to go will vary from the mean by 2.2 students.
A
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
A set of bivariate data was used to create a least-squares regression line. Which of the following is minimized by the line? A The sum of the residuals B The sum of the squared residuals C The sum of the absolute values of the residuals D The influence of outliers E The slope
B
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 19.3mm B 20.6mm C 22.1mm D 23.5mm E 24.9mm
B
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
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 be 0. What does this correlation suggest about the relationship between the time and height? A There is no relationship between time and height. B There is no linear relationship between time and height. C The distance the ball traveled upward is the same as the distance the ball traveled downward. D The correlation suggests that there is measurement or calculation error. E The correlation suggests that more measurements should be taken to better understand the relationship.
B
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 be seniors absent from school on the day the survey is given, which could affect the results. E There is no disadvantage to using a cluster sample.
C
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? A The relationship is linear because the correlation is positive. B The relationship is not linear because the correlation is positive. C The parties with a larger number of customers are associated with the longer times elapsed until the party left the restaurant. D The parties with a larger number of customers are associated with the shorter times elapsed until the party left the restaurant. E There is no relationship between the number of customers in a party at a table in the restaurant and the time required until the party left the restaurant.
C
What value of aa would indicate no association between gender and voting pattern for the people in the sample? A 300 B 400 C 480 D 500 E 800
C
Which of the following describes a continuous variable? A The number of items sold at a craft booth for one day B The number of apps downloaded from a website one day C The diameters of the tree trunks at an evergreen farm D The number of baskets made by a basketball player E The shoe sizes of all shoes on sale at a department store
C
A company is considering purchasing the mineral rights to two different mountains. The probability that it will purchase the mineral rights to the first mountain is 0.55. The probability that it will purchase the mineral rights to the second mountain is 0.4. Assuming the decisions to purchase the mineral rights to each mountain are made independently, what is the probability that it will purchase the mineral rights to exactly one of the two mountains? A 0.18 B 0.22 C 0.33 D 0.51 E 0.95
D
Which of the following statements is not supported by the bar chart? A More than 60% of both tenth-grade and eleventh-grade students responded yes. B Twelfth-grade students had the least percentage of students respond yes. C Less than 40% of tenth-grade students responded no. D The number of tenth-grade students who responded yes was greater than the number of ninth-grade students who responded yes. E The percentage of eleventh-grade students who responded no was less than the percentage of ninth-grade students who responded no.
D
A local employer asked for help selecting a new type of desk chair. Thirty employees volunteered, and each employee used the new desk chair for two weeks and the 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? A It is not a well-designed experiment because employees were allowed to volunteer instead of being randomly selected. B It is not a well-designed experiment because only one new chair was used. At least two new treatments must be used. C It is not a well-designed experiment because each employee was assigned both treatments, and each employee should be assigned only one. D It is not a well-designed experiment because using a coin flip does not guarantee that fifteen employees will use each chair first. E It is a well-designed experiment because there is random assignment, replication, and comparison of at least two treatment groups.
E
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 has only one color, which of the following cannot be the probability that the selected car will be green? A 0 B 0.1 C 0.2 D 0.5 E 0.6
E
The least-squares regression line Sˆ=0.5+1.1LS^=0.5+1.1L models the relationship between the listing price and the actual sales price of 12 houses, with both amounts given in hundred-thousands of dollars. Let LL represent the listing price and SS represent the sales price. Which of the following is the best interpretation of the slope of the regression line? A For each hundred-thousand-dollar increase in the listing price, the sales price will increase by $1.1. B For each hundred-thousand-dollar increase in the listing price, the sales price will increase by $110,000. C For each hundred-thousand-dollar increase in the listing price, the sales price will decrease by $110,000. D For each hundred-thousand-dollar increase in the listing price, the sales price is predicted to increase by $1.1. E For each hundred-thousand-dollar increase in the listing price, the sales price is predicted to increase by $110,000.
E
Which of the following indicates an association between the shooter's choice of direction and the goalie's choice of direction? A The marginal relative frequencies for the shooter and the goalie are equal. B The marginal relative frequencies for the shooter and the goalie are not equal. C The row totals are not equal. D For the goalie, the relative frequency of a direction is equal to the relative frequency conditioned on the shooter's direction. E For the goalie, the relative frequency of a direction is not equal to the relative frequency conditioned on the shooter's direction.
E
