Mult Choice from tests

Your Stats teacher tells you your test score was the 3rd quartile for the class. Which is true? I) You got a 75% on the test II) You can't really tell what this means without knowing the standard deviation. III) You can't really tell what this means unless the class distribution is nearly Normal. A) none of these B) I only C) II only D) III only E) II and III

A) none of these

Medical records indicate that people with more education tend to live longer; the correlation is 0.48. The slope of the linear model that predicts lifespan from years of education suggest that on average people tend to live 0.8 extra years for each additional year of education they have. The slope of the line that would predict years of education from lifespan is A. 0.288 B. 0.384 C. 0.8 D. 1.25 E. 1.67

A. 0.288

For families who live in apartments the correlation between the family's income and the amount of rent they pay is r=0.60. Which is true? I. In general, families with higher incomes pay more in rent. II. On average, families spend 60% of their income on rent. III. The regression line passes through 60% of the (income$, rent$) data points. A. I only B. II only C. I and II only D. I and III only E. I, II, and III

A. I only

If we wish to compare the average PSAT scores of boys and girls taking AP Statistics at this high school, which would be the best way to gather these data? A. census B. SRS C. stratified sample D. observational study E. experiment

A. census

We collect these data from 50 male students. Which variable is categorical? A. eye color B. head circumference C. hours of homework last week D. number of cigarettes smoked daily E. number of TV sets at home

A. eye color

A regression analysis of students' AP Statistics test scores and the number of hours they spent doing homework found that r-squared=.32. Which of these is true? I. 32% of student test scores can be correctly predicted with this model. II. Homework accounts for 32% of your grade in AP Stats III. There's a 32% chance that you'll get the score this model predicts for you. A. none B. I only C. II only D. III only E. I and II

A. none

A basketball player has a 70% free throw percentage. Which plan could be used to simulate the number of free throws she will make in her next five free throw attempts? I Let 0,1 represent making the first shot, 2,3 represent making the second shot,...,8,9 represent making the fifth shot. Generate five random numbers 0-9, ignoring repeats II Let 0,1,2 represent missing a shot and 3,4,...,9 represent making a shot. Generate five random numbers 0-9 and count how many numbers and count how many are in 3- 9 III Let 0,1,2 represent missing a shot and 3,4,...,9 represent making a shot. Generate five random numbers 0-9 and count how many numbers are in 3-9, ignoring repeats a) I only b) II only c) III only d) I and III e) I, II, and III

B

All but one of these statements contains a blunder. Which could be true? a) The correlation between a football player's weight and the position he plays is 0.54 b) The correlation between the amount of fertilizer used and the yield of beans is 0.42 c) The correlation between a car's length and its fuel efficiency is 0.71 miles per gallon d) There is a high correlation (1.09) between height of a corn stalk and its age in weeks e) There is a correlation of 0.63 between gender and political party

B

Another company's sales increase by the same percent each year. The growth is... a) linear b) exponential c) logarithmic d) power e) quadratic

B

It takes a while for new factory workers to master a complex assembly process. During the first month new employees work, the company tracks the number of days they have been on the job and the length of time it takes them to complete an assembly. The correlation is most likely to be a) exactly -1.0 b) near -0.6 c) near 0 d) near +0.6 e) exactly +1.0

B

Placebos are a tool for a) sampling b) blinding c) blocking d) control e) randomization

B

For each pair of variables, indicate what association you expect: positive (+), negative (-), curved (C), or none (N). 1)Number of hours a person has been up past a normal bedtime and number of minutes it takes the person to do a crossword puzzle 2)Length of a student's hair and number of credits the student earned last year 3)Number of days it rained in a month (during the summer) and number of times you mowed your lawn that month 4)Number of hockey games played in Minnesota during a week and sales of suntan lotion in Minnesota during that week 5)Power level setting of a microwave and number of minutes it takes to boil water

1) + 2) N 3) C 4) - 5) -

A botanist is running an experiment on two fertilizers that require different amounts of watering. She has 40 test plots, half of which are in sunny locations, and half are in the shade. She randomly selects 10 sunny plots and 10 shady plots for which to use one fertilizer with its appropriate watering, while the remaining plots are for the other fertilizer with its appropriate watering. Of the following, which is the most important observation about this procedure? a) The variables, fertilizer and water, are confounded b) The variables, fertilizer and sun, are confounded c) The variables, water and sun, are confounded d) No variables are confounded e) There is a hidden lurking variable

A

A company's sales increase by the same amount each year. The growth is... a) linear b) exponential c) logarithmic d) power e) quadratic

A

An advantage to using surveys as opposed to experiments is that a) Surveys are generally cheaper to conduct b) It is generally easier to conclude cause and effect from surveys c) Surveys are generally not subject to bias d) Surveys involve use of randomization e) Surveys can make use of stratification

A

An ice cream stand reports that 12% of the cones they sell are "jumbo" size. You want to see what a "jumbo" cone looks like, so you stand and watch the sales for a while. What is the probability that the first jumbo cone is the fourth cone you see them sell? a) 8% b) 33% c) 40% d) 60% e) 93%

A

Which is true? I Random scatter in the residuals indicates a model with high predictive power II If two variables are very strongly associated, then the correlation between them will be near +1.0 or -1.0. III The higher the correlation between two variables, the more likely the association is based in cause and effect a) none b) I only c) II only d) I and II only e) I, II, and III

A

Which of the following statements is incorrect? a) voluntary response samples often underrepresent people with strong opinions b) Convenience samples often lead to undercoverage bias c) questionnaires with nonneutral wording are likely to have response bias d) There is no way to fix the results if a biased sampling method was employed. e) Nonresponse bias should be avoided because those who do not respond might have different views from those who do respond.

A

the proportion of orange salamanders along a certain stream is known to be 10%. use a normal model to approximate the probability that, for a sample of 100 salamanders along this stream, 20 of them are orange. a) 0.0004 b) 0.1937 c) 0.3707 d) 0.6293 e) 0.9996

A

which of the following statements is true about a 98% confidence interval for a population proportion based on a given sample? I the interval is wider than a 95% CI would be II there is a 98% chance that our interval contains the population proportion III We are 98% confident that all other sample proportions will be in our interval a) I only b) II only c) III only d) I and II e) none

A

The five-number summary of credit hours for 24 students in a statistics class is: Min Q1 Median Q3 Max 13.0 15.0 16.5 18.0 22.0 Which statement is true? A) There are no outliers in the data B) There is at least one low outlier in the data C) There is at least one high outlier in the data D) There are both low and high outliers in the data E) None of the above

A) There are no outliers in the data

The correlation between a family's weekly income and the amount they spend on restaurant meals is found to be r = 0.30. Which must be true? I Families tend to spend about 30% of their incomes in restaurants II In general, the higher the income, the more the family spends in restaurants III The line of best fit passes through 30% of the (income, restaurant$) data points a) I only b) II only c) III only d) II and III only e) I, II, and III

B

Two variables that are actually not related to each other may nonetheless have a very high correlation because they both result from some other, possible hidden, factor. This is an example of a)leverage b) a lurking variable c) extrapolation d) regression e) an outlier

B

Which of these random variables has a geometric model? a) the number of cards of each suit in a 10-card hand b) the number of people we check until we find someone with green eyes c) the number of cars inspected until we find 3 with bad mufflers d) the number of democrats among a group of 20 randomly chosen adults e) the number of aces among the top 10 cards in a well-shuffled deck

B

Which statement about influential points is true? I Removal of an influential point changes the regression line II Data points that are outliers in the horizontal direction are more likely to be influential than points that are outliers in the vertical direction III Influential points have large residuals a) I only b) I and II c) I and III d) II and III e) I, II, and III

B

a can of cherry pie filling contains a mean of 28 ounces and a standard deviation of 1.8 ounces. The contents of the cans are normally distributed. what is the probability that 4 randomly selected cans of cherry pie filling contain a total of more than 118 ounces? a) .47% b) 4.7% c) 1.7% d) 34.7% e) 17%

B

a friend of yours plans to toss a fair coin 200 times. you watch the first 20 tosses ad 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 finishes all 200 tosses? a) 100 b) 105 c) 110 d) 115 e) 150

B

a p-value indicates a) the prob of the observed statistic given that the alternative hypothesis is true b) the prob of the observed statistic given that the null hypothesis is true c) the prob that the alternative hyp is tru d) the prob that the null is tru given the observed stat e) the prob that the null hyp is tru

B

a relief fund is set up to collect donations for the famlilies affected by recent storms. A random sample of 600 people, half of whom were contacted by telephone and half of whom recieved first class mail requests. 26% of those who were contacted by telephone actually made contributions whereas only 15% of the other 300 people made contributions. Which formula calculates the 95% CI for the difference in the proportions of people who make donations? a) (.26-.15) +- 1.96 square root (.205)(.795)/300 b) (.26-.15) +- 1.96 square root (.26)(.74)/300 + (.15)(.82)/300 c) (.26-.15) +- 1.96 square root (.205)(.795)/600 d) (.26-.15)+-1.96square root(.205)(.795)/300+(.205)(.795)/300 e) (.26-.15)+-1.96square root(.205)(.795)/600+(.205)(.795)/600

B

the city council has 6 men and 3 women. if we randomly choose 2 of them to co-chair a committee, what is the probability these chairpersons are the same gender? a) 4/9 b) 1/2 c) 5/9 d) 5/8 e) 7/8

B

1) School administrators collect data on students attending the school. Which of the following variables is quantitative? A) Class (freshman, soph, junior, senior) B) Grade point average C) Whether the student is in AP Classes D) Whether the student has take the SAT E) None

B) Grade point average

Suppose that a Normal model described student scores in a history class. Parker has a standardized score (z-score) of +2.5. This means that Parker A) is 2.5 points above average for the class. B) is 2.5 standard deviations above average for the class. C) has a standard deviation of 2.5 . D) has a score that is 2.5 times the average for the class. E) none of the above.

B) is 2.5 standard deviations above average for the class.

The mean number of hours worked for the 30 males was 6, and for the 20 females was 9. The overall mean number of hours worked is A. 6.5 B. 7.2 C. 7.5 D. none of these E. cannot be determined

B. 7.2

Which of these variables is most likely to follow a Normal model? A. eye color B. head circumference C. hours of homework last week D. number of cigarettes smoked daily E. number of TV sets at home

B. head circumference

It takes a while for new factory workers to master a complex assembly process. During the first month new employees work, the company tracks the number of days they have been on the job and the length of time it takes them to complete an assembly. The correlation is most likely to be A. exactly -1.0 B. near -0.6 C. near 0 D. near +0.6 E. exactly +1.0

B. near -0.6

A consumer group collected information on standard color TVs (no HDTV or large screen sets). They created a linear model to estimate the cost of a TV (in $) based on the screen size (in inches). Which is the most likely value of the slope of the line of best fit? a) 0.15 b) 1.5 c) 15.0 d) 150.0 e) 1500.0

C

A scatterplot of 1/square root(y) vs x shows a strong positive linear pattern. It is probably true that a) the correlation between X and Y is near +1.0 b) the scatterplot of Y vs X also shows a linear pattern c) the residuals plot for regression of Y on X shows a curved pattern d) large values of X are associated with large values of Y e) accurate predictions can be made for Y even if extrapolation is involved

C

A survey of some AP Stats students recorded gender and whether the sutdent was left or right handed. results were summarized in a table like the one shown. if it turned out that the handedness was independent of gender, how many of the AP Stat students were lefty girls? lefty righty total boy 66 girl ? 54 total 20 100 120 a) 4 b) 7 c) 9 d) 10 e) it cannot be determined

C

Residuals are... a) possible models not explored by the researchers b) variation in the data that is explained by the model c) the difference between observed responses and values predicted by the model d) data collected from individuals that is not consistent with the rest of the group e) none of these

C

What is the probability that there is exactly 1 jumbo among the first 6 cones sold by the ice cream stand. given: 12% of cones are jumbo a) 6% b) 12% c) 38% d) 54% e) 84%

C

Which two events are most likely to be independent? a) having a flat tire, and being late for school b) getting an A in math, and getting an A in Physics c) having a driver's license, and having blue eyes d) having a car accident, and having 3 inches of snow today e) being a senior, and leaving campus for lunch

C

Which of the following summaries are changed by adding a constant to each data value? I the mean II the median III the standard deviation A) I only B) III only C) I and II D) I and III E) I, II, and III

C) I and II

4) Which is true of the data shown in the histogram? (see picture in definition) sorry i couldn't get it in the term I) the distribution is approximately symmetric II) the mean and median are approximately equal III) the median and IQR summarize the data better than the mean and standard deviation A) I only B) III only C) I and II D) I and III E) I II and III

C) I and II its about symmetric and mean and median are almost equal

The advantage of making a stem-and-leaf display instead of a dotplot is that a stem-and-leaf display A) Satisfies the area principle. B) Shows the shape of the distribution better than a dotplot. C) preserves the individual data values. D) A stem-and-leaf display is for quantitative data, while a dotplot shows categorical data E) none of the above

C) preserves the individual data values.

2) Which of the following variables would most likely follow a normal model? A) Family income B) heights of singers in a co-ed choir C) weights of adult make elephants D) scores on an easy test E) all of the above

C) weights of adult male elephants

5) Two sections of a class took the same quiz. Section A had 15 students who had a mean score of 80. Section B had 20 students who had a mean score of 90. Overall what was the approximate mean score for all of the students on the quiz? A) 84.3 B)85.0 C)85.7 D) None of these E) It cannot be determined

C)85.7

Variables X and Y have r=0.40. If we decrease each X value by 0.1, double each Y value, and then interchange them (put X on the Y-axis and vice versa), the new correlation will be A. -0.40 B. 0.15 C. 0.40 D. 0.60 E. 0.80

C. .40

The owner of a car dealership planned to develop strategies to increase sales. He hoped to learn the reasons why many people who visit his car lot do not eventually buy a car from him. For one month he asked his sales staff to keep a list of the names and addresses of everyone who came in to test drive a car. At the end of the month he sent surveys to the people who did not buy the car, asking them why. About one third returned the survey, with 44% of those indicating that they found a lower price elsewhere. Which is true? I. The population of interest is all potential car buyers. II. This survey design suffered from non-response bias. III. Because it comes from a sample, 44% is a parameter, not a statistic. A. I only B. II only C. I and II only D. II and III only E. I, II, and III

C. I and II only

A regression model examining the amount of weight a football player can bench press found that 10 cm differences in chest size are associated with 8 kg differences in weight pressed. Which is true? I. The correlation between chest size and wight pressed is r=0.80 II. As a player gets stronger and presses more weight his chest will get bigger III. A positive residual means that the player pressed more than predicted. A. none B. I only C. III only D. I and II E. I and III

C. III only

A researcher finds 200 women over 50 who exercise regularly, pairs each with a woman who has a similar medical history but does not exercise, then follows the subjects for 10 years to see which group develops more cancer. This is a A. survey B. retrospective study C. prospective study D. randomized experiment E. matched experiment

C. prospective study

20 dogs and 20 cats were subjects in an experiment to test the effectiveness of a new flea control chemical. 10 of the dogs were randomly assigned to an experimental group that wore a collar containing the chemical, while the others wore a similar collar without the chemical. The same was done with the cats. After 30 days, veterinarians were asked to inspect the animals for fleas and evidence of flea bits. This experiment is A. complete randomized with one factor: the type of collar B. completely randomized with one factor: the species of animal C. randomized block, blocked by species D. randomized block, blocked by type of collar E. completely randomized with two factors

C. randomized block, blocked by species

A bank wishes to survey its customers. The decision is made to randomly pick 10 customers who just have checking accounts, 10 customers who just have savings accounts, and 10 customers who have both checking and savings accounts. This procedure is an example of which type of sampling? a) Cluster b) Convenience c) Simple random d) stratified e) systematic

D

A least squares line of regression has been fitted to a scatterplot; the model's residuals plot is shown. Which is true? a) The linear model is poor because some residuals are large b) The linear model is appropriate c)The linear model is poor because the correlation is near 0 d) A curved model would be better e) None of the above *picture of curved scatterplot*

D

A researcher wants to compare the effect of a new type of shampoo on hair condition. The researcher believes that men and women may react to the shampoo differently. Additionally, the researcher believes that the shampoo will react differently on hair that is dyed. The subjects are split into four groups: men who dye their hair; men who do not dye their hair; women who dye their hair; women who do not dye their hair. Subjects in each group are randomly assigned to the new shampoo and the old shampoo. This experiment a) Has three factors (shampoo type, gender, whether hair is dyed). b) Has two factors (gender and whether hair is dyed) blocked by shampoo type c)Has two factors (shampoo type and whether hair is dyed) blocked by gender d) Has one factor (shampoo type), blocked by gender and whether hair is dyed

D

Double-blinding in experiments is important so that I The evaluators do not know which treatment group the participants are in II The participants do not know which treatment group they are in III No one knows which treatment any of the participants is getting a) I only b) II only c) III only d) I and II e) I, II, and III

D

If the point in the upper right corner of this scatterplot is removed from the data set, then what will happen to the slope of the line of best fit (b) and to the correlation (r)? a) both will increase b) both will decrease c) b will increase, and r will decrease d) b will decrease, and r will increase e) both will remain the same

D

In a survey of 30 elementary school students, those with larger show sizes appear to have higher reading levels. Of the following, which is the most important conclusion about this observation? a) Parents interested in their child's reading level should have their child wear a slightly larger shoe size b) The variables, shoe size and reading level, are being confounded. c) The sample size is too small for any reasonable conclusion. d) There is a lurking variable e) As long as the sample was randomly selected, a cause-and-effect conclusion is valid

D

Which of the random variables is most likely to have a binomial model? a) the number of cards of each suit in a 10-card hand b) the number of people we check until we find someone with green eyes c) the number of cars inspected until we find 3 with bad mufflers d) the number of democrats among a group of 20 randomly chosen adults e) the number of aces among the top 10 cards in a well-shuffled deck

D

political analysts estimate the probability that Hillary Clinton will run for president in 2008 is 45% and the probability that NY's Governor George Pataki will run as the republican candidate is 20%. If their political decisions are independent then what is the probability that only Hillary runs for president? a) 9% b) 11% c) 25% d) 36% e) 45%

D

we test the hypothesis that p=42% versus p>42%. we don't know it but actually p= 48%. with which sample size and significance level will our test have the greatest power? a) a=0.01, n=250 b) a=0.05, n =250 c) a=0.01, n=400 d) a=0.05, n=400 e) the power will be the same as long as the tru proportion p remains 48%

D

3) a professor has kept records on grades that students have earned in his class. If he wants to examine the percentage of students earning the grades A,B,C,D and F during the most recent term, which kind of plot could he make? A) boxplot B) timeplot C) dotplot D) pie chart E) histogram

D) pie chart

A lakeside restaurant found the correlation between the daily temperature and the number of meals they served to be 0.40. On a day when the temperature is two standard deviations above the mean, the number of meals they should plan on serving is ______ the mean. A. equal to B. 0.16 SD above C. 0.4 SD above D. 0.8 SD above E. 2.0 SD above

D. 0.8 SD above

Suppose we collect data hoping to be able to estimate the prices of commonly owned new cars (in $) from their lengths (in feet). Of these possibilities, the slope of the line of best fit is most likely to be A. 3 B. 30 C. 300 D. 3000 E. 30000

D. 3000

We might choose to display data with a stemplot rather than a boxplot because a stemplot I. reveals the shape of the distribution II. is better for large data sets III. displays the actual data A. I only B. II only C. III only D. I and III E. I, II, and III

D. I and III

Which is true about sampling? I. An attempt to take a census will always result in less bias than sampling. II. Sampling error is usually reduced when the sample size is larger. III. Sampling error is the result of random variations and is always present. A. I only B. II only C. III only D. II and III E. all three

D. II and III

A factory has 20 assembly lines producing a popular toy. To inspect a representative sample of 100 toys, quality control staff randomly selected 5 toys from each line's output. Was this a simple random sample? A. Yes, because the toys were selected at random. B. Yes, because each toy produced had an equal chance to be selected. C. Yes, because a stratified sample is a type of simple random sample. D. No, because not all combinations of 100 toys could have been chosen. E. No, because toys do not come off the assembly line at random.

D. No, because not all combinations of 100 toys could have been chosen.

Which of these variables is most likely to be bimodal? A. eye color B. head circumference C. hours of homework last week D. number of cigarettes smoked daily E. number of TV sets at home

D. number of cigarettes smoked daily

A regression analysis of company profits and the amount of money the company spent on advertising found r^2 = 0.72. Which is true? I This model can corrctly predict the profit for 72% of companies II On average, about 72% of a company's profit results from advertising III On average, companies spend about 72% of their profits on advertising a) I only b) II only c) III only d) I and III e) None

E

Each of the 30 major league baseball teams carries a 40-person roster. A sample of 60 players (5 percent of all 1,200 players) is to be randomly selected to undergo drug tests. To do this, each team is instructed to put their 40 names in a hat and randomly draw two names. Will this method result in a simple random sample of the 1,200 players? a) Yes, because each player has the same chance of being selected b) Yes, because each team is equally represented c) Yes, because this is an example of stratified sampling, which is a special case of simple random sampling d) No, because the teams are not chosen randomly e) No, because not each group of 60 players has the same chance of being selected

E

It's easy to measure the circumference of a tree's trunk, but not so easy to measure its height. Foresters developed a model for ponderosa pines that they use to predict the tree's height (in feet) from the circumference of its trunk (in inches): ln (h-hat) = -1.2 + 1.4 (lnC) A lumberjack finds a tree with a circumference of 60"; how tall does this model estimate the tree to be? a) 5' b) 11' c) 19' d) 83' e) 93'

E

a certain population is bimodal. We want to estimate its mean, so we will collect a sample. which should be true if we use a large sample rather than a small one? I the distribution of our sample data will be more clearly bimodal II the variability of the sample means will be smaller III the sampling distribution of the sample means will be approximately normal a) I only b) II only c) III only d) II and III e) I, II, and III

E

owners of a chain of ice cream shops recently examined sales figures and noticed that on a randomly selected day, 21 of 103 ice cream customers from their shop located in the eastern part of the state ordered soft serve ice cream, while 29 of 132 ice cream customers form their shop located in the western part of the state ordered soft serve ice cream. is there a significant difference in the proportions of customers who favored soft serve ice cream in the eastern and western parts of the state? a) there is a significant difference at the 0.001 level but not at then 0.05 level b) there is a significant difference at the 0.10 level but not at the 0.05 level c) there is a significant difference at the 0.05 level but not at the 0.01 level d) there is a significant difference at the 0.01 level but not at the 0.001 level e) there is no a significant difference at the 0.10 level

E

suppose that a manufacturer is testing one of its machines to make sure that the machine is producing more than 97% good parts (Ho: p= 0.07 and HA: p> 0.97). the test result in a p-value of 0.112. unknown to the manufacturer, the machine is actually producing 99% good parts. What probably happens as a result of the testing? a) they correctly fail to reject Ho b) they fail to reject Ho, making a type 1 error c) they reject Ho, making a type 1 error d) they correctly reject Ho e) they fail to reject Ho, making a type 2 error

E

we have calculated a confidence interval based upon a sample of n=300. Now we want to get a better estimate with a margin of error only one third as large. we need a new sample with n at least... a) 27 b) 270 c) 370 d) 970 e) 2700

E

To check the effect of cold temperatures on the battery's ability to start a car, researchers purchased a battery from Sears and one from NAPA. They disabled a car so it would not start, put the car in a warm garage, and installed the Sears battery. They tried to start the car repeatedly, keeping track of the total time that elapsed before the battery could no longer turn the engine over. Then they moved the car outdoors where the temperature was below zero. After the car had chilled there for several hours, the researchers installed the NAPA battery and repeated the test. Is this a good experimental design? A. Yes B. No, because the car and the batteries were not chosen at random C. No, because they should have tested other brands of batteries, too D. No, because they should have tested more temperature E. No, because temperature is confounded by brand.

E. No, because temperature is confounded by brand

Which is important in designing a good experiment? I. Randomization in assigning subjects to treatments. II. Control of potentially confounding variables. III. Replication of the experiment on a sufficient number of subjects A. I only B. I and II C. I and III D. II and III E. all three

E. all three

Suppose that a Normal model describes the acidity (pH) of rainwater, and that water tested after last week's storm had a z-score of 1.8. That means that the acidity of that rain... A. had a pH of 1.8 B. varied with a standard deviation of 1.8 C. had a pH 1.8 higher than average rainfall D. had a pH 1.8 times that of average rainwater E. had a pH 1.8 standard deviations higher than that of average rainwater

E. had a pH 1.8 standard deviations higher than that of average rainfall

Researcher have 50 volunteers check their pulse rates. Then they watch an action film, after which they take their pulse rates once more. Which aspect of experimentation is present in this research? A. a placebo B. blinding C. randomization D. a control goup E. none of these

E. none of these

Environmental researcher have collected rain acidity data for several decades. They want to see if there is any evidence that attempts to reduce industrial pollution have produced a trend toward less acidic rainfall. They should display their data in a A. contingency table B. bar graph C. boxplot D. histogram E. timeplot

E. timeplot

In this experiment the primary purpose of blocking is to reduce A. bias B. confounding C. randomness D. undercoverage E. variation

E. variation

on a physical fitness test middle school boys are awarded one point for each push-up they can do, and a point for each sit-up. National results showed that boys average 18 push-ups with a standard deviation of 4 push-ups, and 34 sit-ups with a standard deviation 11. the mean of their combined (total) scores was therefore 18+34 = 52 points. what is the standard deviation of their combined scores? a) 5.3 b) 11.7 c) 15 d) 137 e) It cannot be determined

e

The table shows whether students in an introductory statistics class like dogs and/or cats. Like Dogs | Yes | No | Total | Like cats | Yes | 194 | 21 | 215 | No | 110 | 10 | 120 |Total | 304 | 31 | 335 a) What is the marginal distribution (in %) of "liking dogs"? b) What is the conditional distribution (in %) of "liking dogs" for students who like cats? c) what kind of display(s) would you use to examine the association between "liking dogs" and "liking cats"? (just name a graph.) d) Do "liking dogs" and "liking cats" appear to be independent? give statistical evidence to support your conclusion.

first free response question