stats final

A company makes that makes fleece clothing uses fleece produced from two farms, Northern Farm and Western Farm...

A) 1.3+0.5

B) sqrt(1.3^2+0.5^2)

C) sqrt(10(1.3)^2+15(0.5)^2)

D) sqrt(10^2(1.3)^2+15^2(0.5)^2)

E) sqrt((1.3)^2/10 + (0.5)^2/15

C

According to a report for veterinarians in the US, 36.5 percent of households in the US own dogs and 30.4 % own cats...

A) 0.111

B) 0.331

C) 0.558

D) 0.669

E) Not enough info

E

For a recent season in college football, the total number of rushing yards for that season is recorded for each running back. The mean number of rushing yards...

A) 250

B) 300

C) 350

D) 400

E) 450

C

Academia High School collected heights of students in their intramural basketball league. The box plot and statistics below provide a summary of the distribution of heights, in inches. Which conclusion about the distribution is most plausible?

(A) 50% of the students are taller than 68.2 inches.

(B) 75% of the students are taller than 71 inches.

(C) There are more students between 67 inches and 79 inches than are between 62 inches and 67inches.

(D) Less than 25% of the students have heights between 68.2 and 71 inches.

(E) The height that occurs most frequently is 67 inches.

D

Researchers conducting a study of the effectiveness of Tamiflu for reducing the duration of flusymptoms recruited 50 subjects who agreed to report to the researchers' lab within 24 hours ofgetting flu symptoms. Half of the subjects were randomly assigned to take a full dosage of Tamifluand the other half received a placebo. The time (in hours) to alleviation of all flu symptoms for thetwo groups are compared in the back-to-back stemplot below. Which of the following statements is true about the shapes of the distributions of recovery times?

(A) The distributions of recovery times for the Tamiflu and placebo groups are both symmetric.

(B) The distributions of recovery times for the Tamiflu and placebo groups are both skewed to the left.

(C) The distributions of recovery times for the Tamiflu and placebo groups are both skewed to the right.

(D) The distribution of recovery times for the Tamiflu group is skewed to the l

C

Last week, Mrs. Thomas, the AP Statistics teacher at Green Valley High School, gave her studentsan assessment on material they had recently studied. The students' scores on the assessment followedan approximately normal distribution with mean 83.54 and standard deviation 11.21. Andrew, astudent in Mrs. Thomas' class, had a standardized score of z = 0.88. What was Andrew's score on thetest, and in which quarter of the distribution would Andrew's score fall?

(A) 73.68; his score would fall in the first quarter because it is below the first quartile

(B) 73.68; his score would fall in the second quarter because it is between the first quartile and themedian

(C) 84.42; his score would fall in the fourth quarter because it is above the third quartile

(D) 93.40; his score would fall in the fourth quarter because it is above the third quartile

(E) 93.40; his score would fall in the first quarter because it is below the first

D

A study was conducted to test the effect of product price and display level on supermarket sales. At one supermarket, the price level... Identify the treatments used in this experiment.

A) the three price levels used by the supermarket

B) the three display levels used by the supermarket

C) the supermarket

D) the weekly sales for each of the weeks

E) The nine combinations of price and display levels used by the supermarket

E

Consider the following residual plot for the least squares regression line of y versus x. Which of the folloing is an appropriate conclusion based on the residual plot?

A) There is a pattern in the residual plot...

B) There is a strong positive linear relationship...

C) Because there is no pattern in the residual plot...

D) There will be a linear trend apparent in the scatterplot of y versus x, but the data values will tend to...

E) Bc none of the residuals equal zero...

D

Before opening a new restaurant, a chef wants to gather information about the eating habits of thelocal residents. He randomly selects 1000 households from all households in the area and mails aquestionnaire to them. Of the 1000 surveys mailed, he receives 150 back. Which of the following isthe most obvious concern with how this information is gathered?

(A) The 1000 selected households are not a simple random sample of households.

(B) Mailing questionnaires instead of conducting in-person interviews produces a convenience sample.

(C) Those who chose to respond to the survey may have different eating habits from those who didnot respond.

(D) Only residents from the local area were polled.

(E) The chef must conduct a census in order to avoid all sources of bias.

C

Does the color of cards affect a person's ability to sort the cards? Twelve volunteers were asked tosort two sets of 200 cards into two piles. One set of cards were bright red and bright green. Theother set of cards were black and white. The order (red/green first or black/white first) wasdetermined by a coin toss with ample time between the two tasks to lessen the effect of practice.The time (in seconds) to complete each of the two tasks are given in the table below. Assuming the conditions for inference are met, what statistical test should be used to determine ifthere is a significant difference in the mean time required to sort the two sets of cards?

(A) A chi-square goodness-of-fit test

(B) A chi-square test of independence

(C) A matched-pairs t-test for means

(D) A two-sample t-test for means

(E) A linear regression t-tesT

C

Consider a tack like the one pictured below... Which of the following must be true?

A) If the tack is dropped 50 times....

B) If the tack is dropped on a table 10 times...

C) If the tack is dropped on a table 1,000,000 times...

D) Over many tack drops, the prop...

E) the tack landed point down twice in a simple random sample

D

Let X be a random variable that has a skewed right distribution with mean 𝜇𝜇 = 10 and standarddeviation 𝜎𝜎 = 10. Which of the following histograms could display the distribution of the samplemean 𝑥𝑥̅ from many random samples of size 400 from this population?

E (symmetrical)

Beatrice is graduating from college this semester and has received two job offers, one in city A andone in city B. To help her decide where to move, she would like to estimate the difference in averagehome prices for these two cities. From a random sample of 40 listings in city A the average home priceis $190,000 and from a random sample of 40 listings in city B the average home price is $185,000.She finds that the margin of error for a 95% confidence interval for the difference in average homeprice between the two cities (A - B) is $3,250. Which of the following conclusions is correct?

(A) Beatrice can be 95% confident that the average home price is between $1,750 and $8,250 morein city A than in city B.

(B) Beatrice can be 95% confident that the average home price is between $1,750 and $8,250 less incity A than in city B.

(C) Beatrice can be 95% confident that the average home price is $5,000 less in city A than in

A

In a manufacturing process, there are strict tolerances on the dimensions of a part produced. If the partis too long, it must be trimmed to the correct length. Suppose 5% of all parts are too long and 1% of allparts are too short. Parts of the correct length (either originally or trimmed) can be sold for $5 each.However, if the part is too short, it cannot be used at all and is discarded. The cost of manufacturingeach part is $2 and the cost to trim a part to length is $1. The expected profit per part is:

(A) $1.00

(B) $2.05

(C) $2.90

(D) $3.00

(E) $4.95

C

A 2015 survey of 400 randomly selected drivers reported that 20 percent of the drivers surveyednever use their cruise control. A 95% confidence interval is given by (0.161, 0.239). Which of thefollowing is a correct interpretation of the 95% confidence level?

(A) We are 95 percent confident that the true proportion of all drivers who never use their cruisecontrol is between 0.161 and 0.239.

(B) There is a 0.95 probability that the true proportion of all drivers who never use their cruisecontrol is between 0.161 and 0.239.

(C) 95 percent of all random samples of 400 drivers chosen from the population will result inconfidence intervals which contain 0.20.

(D) 95 percent of all random samples of 400 drivers will result in confidence intervals which containthe true proportion of all drivers who never use their cruise control.

(E) 95 percent of all random samples of 400 drivers chosen from the population will have samplep

D

A survey asked male and female students how many text messages they send in one day. The resultsare summarized in the boxplots below.Based on the boxplots, which of the following statements must be true?

(A) There were more females surveyed than males.

(B) Both distributions contain outliers.

(C) The distribution of number of text messages sent by males is approximately normal.

(D) 50% of the females send more text messages than 75% of the males.

(E) The male responses vary more than the female responses.

D

The University of Georgia has several football players participating in the NFL draft this season. Afew former coaches are helping the players prepare for the NFL tryout by tracking their practiceperformance. One coach calculates the athlete's speed in feet per second each round and then findsthe mean and standard deviation for all rounds. Since the workout tested at the NFL tryout is the 40yard dash, the coach decides to convert these speeds to yards per second instead of feet per second,where 1 yard is equal to 3 feet. Which of the following best describes what would happen to thesummary statistics for the athletes?

(A) The mean would increase, but the standard deviation would remain the same.

(B) Both the mean and standard deviation would remain the same.

(C) Both the mean and standard deviation would decrease.

(D) The mean would decrease, but the standard deviation would remain the same.

(E) The mean would decrea

C

In a study of achievement scores, the class size (number of students in the classroom) and the average student achievement for that class are recorded. Let x = class size and y = average achievement. A scatterplot of ln(y) versus x shows a strong negative linear relationship. Output from a regression analysis is shown below.

a) large class or smth

b) the residual plot or smth

C) the correlation between or something

D) there is also a strong negative something

E) lrager valyes of class size or smth

B

The histograms below display the ages of all American males who have been given the namesWilliam and Zachary in the last 50 years. Assume that the two graphs have the same vertical scale. Which group has the smaller standard deviation: males named William or males named Zachary?

(A) Distribution W has the smaller standard deviation because the people are almost evenlydistributed across the age range.

(B) Distribution W has the smaller standard deviation because it shows a weak, positive association.

(C) Distribution Z has the smaller standard deviation because the distribution is slightly skewed tothe left.

(D) Distribution Z has the smaller standard deviation because there are more ages clustered near thecenter of the distribution.

(E) The two distributions have the same standard deviation because the range of ages is the same.

D

A 2017 survey of 1077 registered voters found that 83 percent of the voters surveyed oppose thegovernment's plan to repeal its net neutrality rules for internet providers. The poll's margin of errorwas ±3 percentage points at a 99% confidence level. Which of the following best describes what ismeant by the poll having a margin of error of ±3 percentage points?

(A) Three percent of those surveyed were unavailable to participate in the poll.

(B) It would not be unexpected for 3% of the population to readily agree to the net neutrality rules.

(C) Between 862 and 926 of the 1077 voters surveyed responded that they would oppose thegovernment's plan to repeal its net neutrality rules for internet providers.

(D) The poll used a method that gets an answer within 3% of the truth about the populationapproximately 99% of the time.

(E) Between 80% and 86% of all registered voters oppose the government's plan to repeal its netn

D

A group of students at a local university were asked about their status (undergraduate, graduate, ornon-degree seeking) and how they get to campus (walk/bike or car/bus/etc.). The results aresummarized in the table below. Suppose we choose a person at random from this sample. Which of the following statements is true?

(A) If the person uses a car/bus/etc. to get to campus, then he or she is more likely to be a non-degree seeking student than a degree seeking student (undergraduate or graduate).

(B) If the person is an undergraduate, then he or she is more likely to use a car/bus/etc. to get tocampus than to walk/bike to campus.

(C) The person is more likely be a graduate student if he or she uses a car/bus/etc. to get to campusthan if he or she walks/bikes to campus.

(D) The person is more likely to use a car/bus/etc. to get to campus than to walk/bike to campus.

(E) The person is more likely to be a graduate student

A

Researchers are testing the breaking strength of a new brand of rope using a large sample of ropes.In a test of H0 : p = 0.80 versus Ha: p > 0.80, where p is the true proportion of all ropes of this brandthat would break when subjected to a weight of 1000 pounds, the test statistic is z = 1.45. Which ofthe following is true?

(A) H0 is rejected at the 5% level, but not at the 10% level of significance.

(B) H0 is rejected at the 10% level, but not at the 5% level of significance.

(C) H0 is rejected at both the 5% and 10% level of significance.

(D) H0 is not rejected at both the 5% and 10% level of significance.

(E) H0 is not rejected at any level of significance.

B

Max would like to know whether there is community interest in having local musicians performmusic in the park in the evenings during the summer. Max goes to the park for several evenings in arow and asks people entering the park whether they would like to hear music in the evening. Out ofthe 200 people he surveys, 58% respond favorably. This scenario is describing what type ofsampling?

(A) Simple random sampling

(B) Volunteer sampling

(C) Convenience sampling

(D) Cluster sampling

(E) Stratified sampling

C

Last football season the starting quarterback of a professional football team completed just 55% of his attempted passes... Should he use a sig. level of a= 0.01 or 0.1?

D

The major television networks are interested in knowing what percentage of Super Bowl viewers plan to also stick around to watch the show that airs after it. Which of the following will give the minimum sample size that needs to be surveyed to be 99 percent confident of the true proportion to within +-4 percent?

(A) 2.326

(B) 2.326

(C) 2.576 (large square root thing)

(D) 2.576 * sqrt(n) / 0.5

(E) 2.576 * 0.5 / sqrt(n)

E

Trisomy 18 (T18) is a rare genetic disorder that severely disrupts a baby's development prior to birth.Many die before birth and most die before their first birthday. T18 occurs in only 1 in 2500pregnancies in the U.S. A genetic test on the mother's blood can be done to test for T18 in her baby.The overall probability of a positive test result is 0.010384. The probability of a positive test resultfor a baby with T18 is 0.97. The probability of a negative test result for a baby without T18 is 0.99.A mother's blood tests positive for T18. What is the probability that her baby has T18?

(A) 0.0004

(B) 0.0374

(C) 0.4902

(D) 0.97

(E) 0.99

B

Porsche Cars North America keeps detailed records on all current Porsche owners. The marketingdirector takes a random sample of 9 customer records and finds that the average age of a Porscheowner is 52.8 years with a standard deviation of 6.1 years. Assuming all conditions of inferencewere met, what is a 95% confidence interval estimate for the average age of all Porsche owners?

A (2.306 * 6.1/3)

A roll of Life Savers candies contains 14 pieces. Suppose the individual candies have a mean weightof 0.09 ounces and standard deviation of 0.01 ounces. Find the mean and standard deviation of thetotal weight of the roll of candies, ignoring the weight of any packaging material.

(A) mean = 1.26 ounces, standard deviation = 0.0014 ounces

(B) mean = 1.26 ounces, standard deviation = 0.037 ounces

(C) mean = 1.26 ounces, standard deviation = 0.14 ounces

(D) mean = 0.09 ounces, standard deviation = 0.037 ounces

(E) mean = 0.09 ounces, standard deviation = 0.14 ounces

B

The time that an Olympic skier takes on a downhill course has a normal distribution with a mean of85.5 seconds and standard deviation of 0.8 seconds. The probability that on a random run the skiertakes between 85.1 and 85.9 seconds is:

(A) 0.1915

(B) 0.3085

(C) 0.3830

(D) 0.6170

(E) 0.6826

C

Reading and understanding nutrition labels on foods may be an important precursor to dietarychange. Researchers randomly selected four medical clinics in Missouri. A total of 885 patients wereasked to complete a survey while waiting to see their physicians. The study found that those whoread labels tended to have better diets. Can the researchers conclude that reading nutrition labels onfoods causes patients to have better diets?

(A) No, because the 885 respondents do not represent a simple random sample.

(B) No, this was an observational study so the researchers can only claim an association.

(C) Yes, because the use of randomization in the study allows for cause and effect conclusions.

(D) Yes, because the sample size of 885 is sufficiently large.

(E) The researchers can only claim a cause and effect relationship among individuals similar to thepatients who completed the survey.

B

A research specialist for a large seafood company plans to investigate bacterial growth on oysterssubjected to two different storage temperatures, 0 and 10 degrees Celsius. There are 18 refrigeratorsavailable for the experiment, six each of three different brands (Brand A, Brand B and Brand C).Each refrigerator has been stocked with a random selection of fresh oysters harvested from the samebody of water. For each brand, the researcher randomly selects three refrigerators to set at 0 degreesCelsius and the other three are set at 10 degrees Celsius. At the end of the storage period, thebacterial count will be determined on all the oysters and the average count for the two temperatureswill be compared within refrigerator brand. For this experiment, identify the blocking factor, if any.

(A) There are no blocks in this experiment

(B) The type of seafood

(C) The temperature level

(D) The refrigerator brand

(E) The bacteri

D

Powerball is a national lottery with drawings held twice a week. Players buy a ticket for $2 for achance to win monetary prizes ranging from $4 to the jackpot which can be in the hundreds ofmillions of dollars. Let X be a player's winnings (in dollars) on one ticket. For a cash jackpot of$100,000,000, E(X) = 0.66. Interpret the value of E(X).

(A) Each player will win $0.66 per ticket.

(B) The probability of winning any monetary prize is 0.66.

(C) The lottery can expect to profit $0.66 per ticket purchased.

(D) The lottery can expect to pay out 66% of the jackpot in prize money.

(E) Over many players, the average winnings per ticket will be close to $0.66

E

A linear regression analysis reveals a strong, negative linear relationship between x and y. Which ofthe following could possibly be the results from this analysis?

E (y = 0.85 - 0.25x)

A survey of 120 randomly selected married couples asked each partner to rate how often they dine out as a couple...

C

A local university surveyed a large random sample of students at the end of their freshmen year in2017 and asked them to report their level of satisfaction with the university. To which of thefollowing populations can the results of this survey be safely generalized?

(A) All university students

(B) All students at this local university

(C) All freshmen university students

(D) Only students who were freshmen at this local university in 2017

(E) Only the freshmen students at this local university in 2017 who were in the survey

D

A group of chemical engineers are trying to determine the cost of refining a mixture based on theconcentration of a particular chemical. After refining 50 samples of the mixture and recording thecost they fit a simple linear regression model to the data. Partial computer output is given below. A scatterplot of cost versus concentration had a moderately, strong curved relationship. Based onthese results, what conclusion can be drawn from this analysis at the 5% significance level?

(A) There is evidence of a significant positive linear relationship between concentration and cost.

(B) There is evidence of a significant negative linear relationship between concentration and cost.

(C) There is evidence of a significant linear relationship between concentration and cost but thedirection is unknown.

(D) There is evidence of a significant non-linear relationship between concentration and cost.

(E) The analysis is inconclusiv

E

Earthworms of the species Lumbricus terrestris often surface after a large rain storm. It is unclearwhy they surface in such abundance after large amounts of rain. The lengths of this species ofearthworm are normally distributed with an average length of 180 mm with a standard deviation of15.5 mm. What length would we expect to find at the 30th percentile?

(A) 22.54

(B) 78.89

(C) 109.89

(D) 171.87

(E) 188.13

D

In a random sample of 400 private high school students, 320 said they brought a smartphone toschool that day, while in a random sample of 400 public high school students, 288 said they broughta smartphone to school that day. Which of the following represents a 98 percent confidence intervalestimate for the difference (private high school minus public high school) between the proportions ofall private high school and public high school students who bring a smartphone to school?

C (2.326 * (0.8)(0.2))

The following computer output contains the results from fitting a simple linear regression model topredict the weight (in pounds) of a vehicle from its city mileage (in miles/gallon) based on a randomsample of 25 cars. Assuming the conditions for inference are satisfied, which of the following gives a 95 percentconfidence interval for the true slope of the regression line based on this model?

(A) −145.57 ± (1.96)(16.258)

(B) −145.57 ± (2.069)(3.2516)

(C) −145.57 ± (2.069)(16.258)

(D) −145.57 ± (8.95)(3.2516)

(E) −145.57 ± (8.95)(16.258)

C

A company that sells quality dishware has two manufacturing plants. In a quality control inspectionof a random sample of 200 dishes from plant A, 8% of the dishes had at least one defect. In arandom sample of 200 dishes from plant B, 5% of the dishes had at least one defect. To determine ifthere is convincing evidence that the true proportion of defective dishes from plant A is more thanthe true proportion of defective dishes from plant B, you test the hypotheses H0 : 𝑝A − 𝑝B = 0 versus Ha: 𝑝A − 𝑝B > 0 and obtain a p-value of 0.112.Which of the following is an appropriate interpretation of this p-value?

(A) If the true proportion of defective dishes at plant A is more than the true proportion of defectivedishes at plant B, there is a 0.112 probability of getting samples with a difference 𝑝𝑝̂A − 𝑝𝑝̂B equalto 0.03.

(B) If the true proportion of defective dishes at the two plants are equa

C

One of the side effects of flooding a lake in northern Nthacoochie Park (e.g., for a hydro-electricproject) is that mercury is leached from the soil, enters the food chain, and eventually contaminatesthe fish. The concentration in fish will vary among individual fish because of differences in eatingpatterns, movements around the lake, etc. Suppose that the concentrations of mercury in individualfish follows an approximate normal distribution with a mean of 0.25 ppm and a standard deviation of0.08 ppm. Fish are safe to eat if the mercury level is below 0.30 ppm. Approximately whatpercentage of fish are safe to eat?

(A) 23%

(B) 27%

(C) 37%

(D) 63%

(E) 73%

E

The week before the bill to repeal Obamacare came up for consideration in the Senate, one pollingagency increased the size of the random sample of U.S. adults they surveyed on this issue from 500 to1500. What effect would this increase have on the polling agency's estimate of the proportion of U.S.adults in favor of repealing Obamacare, assuming the true proportion in favor remained constant?

(A) A reduction in the variability of the estimate

(B) An increase in the variability of the estimate

(C) A reduction in the bias of the estimate

(D) An increase in the bias of the estimate

(E) A reduction in both the variability and the bias of the estimate

A

A reading specialist at Pleasantville High School suspects that there is a difference in the averagereading speed between senior boys and senior girls at the high school. To test her claim, randomsamples of 25 senior boys and 25 senior girls were selected. The reading speed of each student wasmeasured. The reading specialist uses the data obtained to test the hypotheses H0 : 𝜇boys − 𝜇girls = 0 versus Ha: 𝜇boys − 𝜇girls ≠ 0 where 𝜇boys and 𝜇girls are the true mean reading speed of all seniors boysand girls at Pleasantville High School.Which of the following statements best describes a Type I error?

(A) The reading specialist finds evidence there is a difference in the average reading speed betweensenior boys and senior girls at the high school when, in fact, there is a difference in the averagereading speed between senior boys and senior girls.

(B) The reading specialist fails to find evidence

D