AP Stats Midterm Exam

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A child psychologist asked 100 five year olds and 50 ten year olds to name their favorite color. Their results are shown in the following table. Which of the following is supported by the table? A. the percentage of five year olds who selected red or blue as their favorite color is greater than the percentage of ten year olds who selected red or blue as their favorite color. B. the percentage of five year olds who selected yellow as their favorite color is greater than the percentage of ten year olds who selected yellow as their favorite color. C. the percentage of children who selected red, yellow, or blue as their favorite color was equal for both ages. D. less than 1/2 of the five year olds selected red, yellow, or blue as their favorite color. E. less than 1/2 of the ten year olds selected red, yellow, or blue as their favorite color.

A company determines the mean and standard deviation of the number of sick days taken by its employees in one year. Which of the following is the best description of the standard deviation? A. appox the mean distance between the number of sick days taken by individual employees and the mean number of sick days taken by all employees B. approx the median distance between the number of sick days taken by individual employees and the median number of sick days taken by all employees C. the distance between the greatest number of sick days taken by an employee and the mean number of sick days taken by all employees D. the number of days separating the fewest sick days taken and the most sick days when considering all employees E. the number of days separating the fewest sick days taken and the most sick days taken when considering the middle 50 percent of the distribution.

A random sample of 374 United States pennies was collected, and the age of each penny was determined. According to the boxplot below, what is the approximate interquartile range (IQR) of the ages? A. 8 B. 10 C. 16 D. 40 E. 50

A roadrunner is a desert bird that tends to run instead of fly. while running, the roadrunner uses its tail as a balance. a sample of 10 roadrunners as taken, and the birds' total length, in centimeters (cm), and tail length, in cm, where recorded. the output shown in the table is from a least-squares regression to predict tail length given total length. 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, bc the residual is positive B. underestimate, bc the residual is negative C. overestimate, bc the residual is positive D. overestimate, bc the residual is negative E. neither, bc the residual is 0.

100 volunteers who suffer from severe depression are available for a study. Fifty are selected at random and are given a new drug that is thought to be particularly effective in treating severe depression. A psychiatrist evaluates the symptoms of all volunteers after 4 weeks in order to determine if there has been substantial improvement in the severity of the depression. the study would be double blind if A. neither drug had any identifying marks on it B. all volunteers were not allowed to see the psychiatrist nor the psychiatrist allowed to see the volunteers during the session in which the psychiatrist evaluated the severity of the depression C. the patients were given a placebo D. neither the volunteers nor the psychiatrist knew which treatment any person had received E. all of the above

A sample of 15 golfers who played a golf course on a certain day was selected. for each golfer, the average driving distance (x), in yards, and the percent of fairways hit on the drive (y) were recorded. the scatterplot displays the percent of fairways hit versus the avg. driving distance. also shown is the least-squares regression line, y = 66.228 + 0.0002x. the point circled on the scatterplot is considered an influential point. a new least-squares regression line will be calculated with the influential point removed. how will the removal of the influential point affect the new least-squares regression line for the remaining 14 points? A. the y-intercept will remain the same, and the slope will be negative B. the y-intercept will decrease, and the slope will be negative C. the y-intercept will decrease, and the slope will be positive D. the y-intercept will increase, and the slope will be negative E. the y-intercept will increase, and the slope will be positive.

clear-cut harvesting of wood from forests creates long periods of time when certain animals cannot use the forests as habitats. partial-cut harvesting is increasingly used to lessen the effects of logging on the animals. the following scatterplot shows the relationship between the density of red squirrels, in squirrels per plot, 2 to 4 years after partial-cut harvesting, and the percent of trees that were harvested in each of 11 forests. 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 school is having a contest in which students guess number of candies in a jar. The student whose guess is closest to the correct # of candies in the jar wins a prize. The # of candies guessed by male and female students is shown in the back-to-back stemplot below. Which of the following is true about the distribution of guesses? A. The distribution of guesses for male students is skewed to the left, and the distribution of guesses for female students is skewed to the right. B. The distribution of guesses for male students is skewed to the right, and the distribution of guesses for female students is skewed to the left. C. The distribution of guesses for male and female students are both skewed to the right D. The distribution of guesses for male and female students are both skewed to the left. E. The distribution of guesses for male and female students are both symmetric.

I toss a penny and observe whether it lands heads up or tails up. suppose the penny is fair, i.e., the probability of heads is 1/2 and the probability of tails is 1/2, this means that A. every occurence of a head must be balanced by a tail in one of the next two or three tosses B. if i flip the coin 10 times, it would be almost impossible to obtain 7 heads and 3 tails C. if i flip the coin many, many times the proportion of heads will be appox 1/2, and this proportion will tend to get closer and closer to 1/2 as the number of tosses increases. D. regardless of the number of flips, half will be heads and half tails. E. all of the above

Professor James gave the same test to his three sections of statistics students. On the 35-question test, the highest score was 32 and the lowest was 15. Based on the information displayed in the boxplots above, which of the following statements is true? A. section 1 has the smallest interquartile range B. the lowest score in section 2 is higher than the highest score in either of the other sections. C. section 2 has the smallest range of scores. D. the top 25% of scores in section 2 are lower than the highest score in section 3. E. at least 50% of the scores in section 3 are higher than all of the scores in section 1.

The Venn Diagram below describes the proportion of students who take chemistry and spanish at jefferson high school. where A = student takes chemistry and B = students takes spanish Find the value of P(A n B^c) and describe it in words A. 0.1; the probability that the student takes both chemistry and spanish B. 0.3; the probability that the student takes both chemistry and spanish C. 0.5; the probability that the student takes chemistry but not spanish D. 0.2; the probability that the student takes chemistry but not spanish E. 0.6; the probability that the student takes chemistry or spanish

The distributions of four variables are shown below. Which of the following shapes is NOT represented by one of the four distributions? A. uniform B. bimodal C. skewed to the left D. skewed to the right E. symmetric and bimodal

The following list shows the selling prices of 8 houses in a certain town. What is the median selling price of the houses in the list? A. 263,200 B. 283,300 C. 288,450 D. 290,600 E. 293,400

Three brands of candy pieces--X, Y, and Z-- are made in many colors. Shaela bought on ebag of each brand and counted the number of pieces of each color. The graph below shows the relative frequency distribution of colors for each bag. Which of the following statements must be true? A. for brand X, there were more green candy pieces than red candy pieces in the bag. B. for brand Y, there were more red candy pieces than green candy pieces in the bag. C. there were more green candy pieces in the brand X bag than there were in the brand Z bag. D. there were the same number of blue candy pieces in the brand X bag as were in the brand Y bag. E. the number of blue candy pieces in the brand Z bag was equal to the sum of the number of blue candy pieces in the other two bags.

a local tax reform group polls the residents of the school district and asks the question, "do you think the school board should stop spending taxpayers' money on non-essential arts programs in elementary schools?" the results of this poll are likely to A. underestimate support for arts programs bc of nonsampling error. B. overestimate support for arts programs bc of nonsampling error. C. underestimate support for arts programs bc of undercoverage D. accurately estimate support for arts programs. E. overestimate support for arts programs bc of undercoverage

a public opinion poll in Ohio wants to determine whether or not registered voters in the state approve of a measure to ban smoking in all public areas. they select a simple random sample of fifty registered voters from each county in the state and ask whether they approve or disapprove of the measure. this is an example of a A. simple random sample B. systematic sample C. systematic random sample D. cluster sample E. stratified random sample

a researcher collected data on the age, in years, and the growth of sea turtles. the following graph is a residual plot of the regression of growth versus age. does the residual plot support the appropriateness of a linear model? A. yes, bc there is a clear pattern displayed in the residual plot. B. yes bc abt 1/2 the residuals are positive and other half aren't C. yes, bc as age increases, the residuals increase. D. no, bc the pts appear to be randomly distributed. E. no, bc the graph displays a U-shaped pattern.

a researcher in alaska measured the age (in months) and the weight (in pounds) of a random sample of adolescent moose. when the least-squares regression analysis was performed, the correlation was 0.59. which of the following is the correct way to label the correlation? A. 0.59 months per pound B. 0.59 pounds per month C. 0.59 D. 0.59 months times pounds E. 0.59 month pounds

a set of bivariate data was used to create a least-squares regression line. which of the following is minimized by the line? A. sum of residuals B. sum of squared residuals C. sum of absolute values of the residuals D. influence of outliers E. the slope

a sportswriter wants to know how strongly Lafayette residents support the local minor league baseball team, the Lafayette Leopards. She stands outside the stadium before a game and interviews the first 20 people who enter the stadium. The intended population for this survey is A. all leopard fans. B. all people attending the game the day the survey was conducted. C. all american adults. D. the 20 people who gave the sportswriter their opinion. E. all residents of Lafayette.

a sportswriter wants to know how strongly Lafayette residents support the local minor league baseball team, the Lafayette Leopards. She stands outside the stadium before a game and interviews the first 20 people who enter the stadium. the sample for the survey is A. all leopard fans. B. all people attending the game the day the survey was conducted. C. the 20 people who gave the sportswriter their opinion. D. the sportswriter. E. all residents of Lafayette.

a study of elementary school children, ages 6 to 11, finds a high positive correlation between shoe size x and score y on a test of reading comprehension. the observed correlation is most likely due to A. cause and effect (larger shoe siz causes higher reading comprehension). B. the effect of a lurking variable, such as age C. "reverse" cause and effect (higher reading comprehension causes larger shoe size) D. a mistake, since the correlation must be negative E. several outliers in the data set

an airline record the number of on-time arrivals for a sample of 100 flights each day. the boxplot below summarizes the recorded data for one year. based on the boxplot, which of the following statements must be true? A. the range of the number of on-time arrivals is greater than 90. B. the interquartile range of the number of on-time arrivals is 22. C. the number of days that had at least 80 on-time arrivals is greater than the number of days that had at most 76 on-time arrivals. D. the number of days that had 76 to 80 on-time arrivals is equal to the number of days that had at most 76 on-time arrivals. E. the difference between the median and the lower quartile for the number of on-time arrivals is less than 2.

an experiment compares the taste of a new spaghetti sauce with the taste of a commercially successful sauce readily available in grocery stores. each of a number of tasters tastes both sauces (in random order) and says which tastes better. this is called a A. stratified random sample B. simple random sample C. completely randomized design D. matched pairs design E. double-blind design

at a college the scores on the chemistry final exam are appro normally distributed, with a mean of 75 and a standard deviation of 12. the scores on the calculus final are also appox normally distributed, with a mean of 80 and a standard deviation of 8. a student scored 81 on the chemistry final and 84 on the calculus final. relative of the students in each respective class, in which subject did this student do better? A. the student did better in chemistry. B. the student did better in calculus. C. the student did equally well in each course. D. there is no basis for comparison since the subjects are different from each other and are in different departments. E. there is not enough info for comparison bc the number of students in each class is not known.

at a photography contest, entries are scored on a scale from 1 to 100. at a recent contest with 1000 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.

dwayne has collected data on the number of occupants of cars travelling on the road past his house for the past week. based on his data, he has constructed a probability model for the number of occupants of a randomly-selected car on his street. which of the following could be his model? A. No. Prob. 1 .6 2 .2 3 .1 4 .1 >/= 5 .05 B. No. Prob. 1 .5 2 .25 3 .15 4 .06 >/= 5 .04 C. No. Prob. 1. 2 2. 1 3. .1 4. .1 5. .4

event A has probability 0.4, event B has probability 0.5. if A and B are independent, then the probability that both events occur is A. 0.0 B. 0.1 C. 0.2 D. 0.7 E. 0.9

for a specific species of fish in a pong, 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, bc 3 in falls above the max value of lengths in the sample B. yes, bc the regression equation is based on a random sample C. yes, because the association between length and weight is positive D. no, bc 3 in falls above the max value of lengths in the sample E. no, bc there may not be any 3-in fish of this species in the pond

height, in meters, is measured for each person in a sample. after the data is collected, all the height measurements are converted from meters to centimeters by multiplying each measurement by 100. which of the following statistics will remain the same for both units of measure? A. the mean of the height measurements B. the median of the height measurements C. the standard deviation of the height measurements D. the maximum of the height measurements E. the z-scores of the height measurements

if you buy one ticket in the provincial lottery, then the probability that you will win a prize is 0.11. given the nature of lotteries, the probability of winning is independent from month to month. if you buy one ticket each month for five months, what is the probability that you will win at least one prize? A. 0.55 B. 0.50 C. 0.44 D. 0.45 E. 0.56

in a large set of data that is approx normally distributed, r is the value in the data set that has a z score of -1.00. s is the value of the first quartile, and t is the value of the 20th percentile. which of the following is the correct order from least to greatest for the values of r, s, and t? A. r,s,t B. r,t,s C. s,t,r D. t,r,s E. t,s,r

in order to assess the effects on reducing cholesterol, a researcher took a random sample of 50 people from a local gym who exercises regularly and another random sample of 50 people from the surrounding community who did not exercise regularly. they all reported to a clinic to have their cholesterol measured. the subjected were unaware of the purpose of the study, and the technician measuring the cholesterol was not aware of whether or not subjects exercised regularly. Which of the following best describes the inferences the researcher can make based in his results? A. there is not enough info to make judgments about the scope of inference. B. he can make inferences about the populations from which the samples were taken, but not about cause and effect C. he can make inferences abt both cause and effect and the populations from which the samples were taken D. he can make inferences about cause and effect, but not about the populations from which the samples were taken E. he cannot make inferences about either cause and effect or the populations from which the samples were taken

just before the presidential election of 1936, the magazine literary digest predicted incorrectly, as it turned out, that Alf Landon would defeat FDR. Landon lost in a landslide. It turned out that the magazine had only polled its own subscribers, plus others from a list of automobile owners and a list of people who had telephone service. all three groups had higher than typical incomes during the great depression. this is an example of A. nonresponse B. undercoverage C. bias resulting from question wording D. voluntary response bias E. response bias

of the following dotplots, which represents the set of data that has the greatest standard deviation? A. * * * * * B. **** **** C. *** *** *** D. **** ** **** E. ** ** ** ** **

on base percentage plus slugging (OPS) is a statistic used in baseball to measure a team's batting success. the number of runs scored and OPS for 30 baseball teams was used to conduct a linear regression analysis. the scatterplot and computer output for the regression analysis is shown. which of the following is the most appropriate interpretation of the statistic 93.47% in the regression output? A. there is a strong, positive, linear relationship between number of runs scored and OPS. B. the typical deviation between observed and predicted number of runs scored is 0.9347. C. for each one-unit increase in OPS, the regression model predicts an increase of 93.47 runs scored. D. 93.47% of the observed number of runs scored are close to the regression line. E. 93.47% of the variation in number of runs scored can be explained by the linear regression with OPS.

one statistic calculated for pitchers in baseball is called the earned run averge, 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. interquartile range C. median D. minimum E. maximum

researchers wish to determine if a new experimental medication will reduce the symptoms of allergy sufferers without the side effect of drowsiness. to investigate this question, the researchers randomly assigned 100 adult volunteers who suffer from allergies to two groups. they gave the new medication to the subjects in one group and n existing medication to the subjects in the other group. 44% of those in the treatment group and 28% of those in the control group reported a significant reduction in their allergy symptoms without any drowsiness. The experimental units are the A. all the volunteers who did not report a significant reduction in their allergy symptoms without any drowsiness. B. all the volunteers who reported a significant reduction in their allergy symptoms without any drowsiness. C. researchers D. 100 adult volunteers. E. pills containing the new experimental medication

researchers wish to determine if a new experimental medication will reduce the symptoms of allergy sufferers without the side effect of drowsiness. to investigate this question, the researchers randomly assigned 100 adult volunteers who suffer from allergies to two groups. they gave the new medication to the subjects in one group and n existing medication to the subjects in the other group. 44% of those in the treatment group and 28% of those in the control group reported a significant reduction in their allergy symptoms without any drowsiness. which of the following best describes the inferences the researchers can make based in his results? A. they can make inferences about the populations from which the samples were taken, but not about cause and effect B. they can make inferences about cause and effect, but not about the populations from which the samples were taken C. they can make inferences about both cause and effect and the populations from which the samples were taken D. there is not enough info to make judgments abt the scope of inference E. they cannot make inferences abt either cause and effect or the populations from which the samples were taken

scientists estimate that the distribution of the life span of the Galapagos Islands giant tortoise is approx normal with mean 100 years and standard deviation 15 years. based on the estimate, which of the following is closest to the age of a Galapagos Islands giant tortoise at the 90th percentile of the distribution? A. 80 years B. 115 years C. 120 years D. 125 years E. 130 years

the following boxplot shows the typical gas mileage, in miles per gallon, for 20 different car models. Based on the boxplot, the top 25% 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

the following numbers appear in a table of random digits: 38683, 50279, 38224, 09844, 13578, 28251, 12708, 24684 a scientist will be measuring the total amount of leaf litter in a random sample (n=5) of forest sites selected without replacement from a population of 45 sites. the sites are labeled 01, 02, . . . , 45 and she starts at beginning of the line of random digits and takes consecutive pairs of digits. Which of the following is correct? A. her sample is 38, 65, 35, 02, 79 B. her sample is 38, 35, 27, 28, 08 C. her sample is 38, 35, 02, 22, 40 D. her sample is 38, 68, 35, 02, 22 E. her sample is 38, 25, 02, 38, 22

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 x 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. -0.2 D. 0.8 E. 1.8

the most important advantage of experiments over observational studies is that A. experiments are usually easier to carry out B. experiments can give better evidence of causation C. confounding cannot happen in experiments D. observational studies cannot use random samples E. an observational study cannot have a response variable

to determine the proportion of each color of peanut butter M&M, you buy 10 1.69 ounce packages and count how many there are of each color. this is an example of A. simple random sampling B. stratified random sampling C. multistage sampling D. systematic random sampling E. cluster sampling

Data were collected on 100 US coins minted in 2018. Which of the following represents a quantitative variable for the data collected? A. type of metal used in coin B. value of coin C. color of coin D. person on the face of coin E. location where coin was minted

X Y 1 3 2 4 3 7 4 8 5 12 The table shows several values of x and their corresponding values of y. which of the following is closest to the correlation between x and y? A. -0.98 B. -0.95 C. 0.20 D. 0.95 E. 0.98

in order to assess the opinion of students at the university of minnesota on campus snow removal, a reporter for the student newspaper interviews the first 12 students he meets who are willing to express their opinion. the method of sampling used is A. a systematic sample B. a census C. a voluntary sample D. a convenience sample E. a simple random sample

students at university X must have one of four class ranks--freshman, sophomore, junior, or senior. at university X, 35% of the students are freshman and 30% are sophomores. If a university X student is selected at random, the probability that he or she is either a junior or a senior is A. 30% B. 35% C. 65% D. 70% E. 89.5%

the distribution of housing prices in a city includes several outliers at the upper end of the distribution and no outliers at the lower end of the distribution. Which of the following is the most resistant, or robust measure of center of the distribution of housing prices? A. the mean, bc it is affected by the outliers. B. the mean, because it is not greatly affected by the outliers. C. the median, because it is affected by the outliers. D. the median, because it is not greatly affected by the outliers. E. the mode, because the data are categorical.

the number of hurricanes reaching the east coast of the US was recorded for each of the last ten decades by the national hurricane center. summary measures are shown below. Min = 12 Max = 24 Lower Quartile = 15 Upper Quartile = 18 Median = 16 n = 10 Which of the following statements is true? A. the smallest observation is 12 and it is an outlier. no other observations in the data set could be outliers. B. the largest observation is 24 and it is an outlier. no other observations in the data set could be outliers. C. both 12 and 24 are outliers. it is possible that there are also other outliers. D. 12 is an outlier and it is possible that there are other outliers at the low end of the data set. There are no outliers at the high end of the data set. 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.

which of the following histograms has a shape that is approximately uniform? A. B. C. D. E.

which of the following statistics is defined as the 50th percentile? A. the mean B. the median C. the mode D. the interquartile range E. the standard deviation

you draw two marbles at random from a jar that has 20 red marbles and 30 black marbles without replacement. what is the probability that both marbles are red? A. 0.1551 B. 0.1600 C. 0.2222 D. 0.4444 E. 0.8000

you want to use simulation to estimate the probability of getting exactly one head and one tail in two tosses of a fair coin. you assign the digits 0,1,2,3,4 to heads and 5,6,7,8,9 to tails. using the following random digits to execute 10 simulated trials, what is your estimate of the probability? 19226, 95034, 05756, 07118 A. 1/20 B. 1/10 C. 5/10 D. 6/10 E. 2/3

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