AP Stat Barron's Topic 1-9 Answers
auditor working for a veterinary clinic
$114 $30
Science majors in college paying for books
$185 $158
Starting salaries of a graduating class: What is the mean starting salary?
$30,533
for an advertising promotion an auto dealer hands out 1000 lottery tickets: for someone with a single ticket , what is the standard deviation for the amount won?
$790.17
during the 2015 season, Anthony Rizzo and Chris Bryant getting hits were independent events: what was the probability of Bryant getting a hit?
(The probability of both getting hits ) DIVIDED BY ( The probability of Rizzo getting a hit and Bryant not getting a hit) PLUS ( The probability of both getting heads)
tennis winning game proportions : what was the associated residual?
0.028
suppose that, in a certain part of the world, in any 50 year. The probability of a major plague is .39: what is the probability of a famine given that there is a plague?
0.15 DIVIDED BY 0.39
what is the probability of B if A and B are mutually exclusive? If a and B are independent?
0.2, 0.33
what will the new correlation be if 0.14 is added to all values of the X variable, every value of the Y variable is doubled, and the two variables are Interchanged?
0.23
boxes of 50 donut holes
0.3 oz 0.02 oz
what is the probability that a 20-year-old will survive to be 70?
0.579
winning percentage professional baseball teams, regression line: what is the residual if a team has a winning percentage of 55% with an average attendance of 34,000?
0.8
Tennis facing and back: what is the correlation?
0.993
If every woman married a man who was exactly 2 inches taller than she, what would the correlation between the heights of married men and women be?
1
The yearly mortality rate for American men from prostate cancer has been constant for decades: in a group of 100 American men, what is the probability that at least one will die from prostate cancer in a given year?
1 - (0.99975) ^100
A city water supply system involves three pumps, The failure of any of which crashes the system: assuming the pumps operate independently of each other what is the probability that the system does crash during the year?
1 - (1-0.025)(1-0.034)(1-0.02)
Grade point averages for a large public high school: what is the interquartile range?
1.0
dotplot shows speeds of 100 fastballs: which of the following is the best estimate of the standard deviation of these speeds?
1.1 mph
A home theater projector system technician
1.3 hr 0.15 hr
Supposed 10% of a data set lie between 40 and 60. If five is added to each value in the set and then each result is doubled, which of the following is true?
10% of the resulting data will lie between 90 and 130
according to a CBS poll taken in 1992, 15% of the public have responded to a telephone call in poll: In a random group of five people, what is the probability that exactly to have responded to a call in poll?
10(0.15)(0.85)
if 75% of all families spend more than $75 weekly for food, while 15% spend more than $150, what is the mean weekly expenditure and what is the standard deviation?
104.39 43.86
cucumbers grown on a certain farm: what is the mean weight if 85% of the cucumbers weigh less than 16 ounces?
13.92
what is the approximate median age of the Liberian population?
15-19
Grade point average is for a large public high school: what is the median grade point average
2.4
Given that 10% of nails made using a certain manufacturing process have a length less than 2.48 inches while 5% have a length greater than 2.54 inches : what are the mean and standard deviation of the length of nails ?
2.506 0.0205
Jay Olshansky from the university of Chicago was quoted: what standard deviation is he assuming for this statement to make sense?
21.7
suppose we have a random variable X wear for the values K equals zero, ..., 10: what is the mean of X?
3.7
College freshman SAT scores, resulting regression equation: what percentage of the variation in GPAs can be explained by looking at the linear relationship between GPAs and SAT scores?
39.9%
if X and Y are the sample means of the X and Y values, respectively, then Y =
3x-1
Average score is 500, standard deviation is 100: If each score is increased by 25, what are the new mean and standard deviation?
525, 100
given any straight line, we can calculate the sum of the squares of the three vertical distances from these points to the line. What is the smallest possible value this sum can be?
6
A coffee machine can be adjusted to deliver any fixed number of ounces of coffee: what should be the mean setting so that an 8 ounce cup will overflow only 0.5% of the time
6.97 ounces
Average score is 500, standard deviation is 100: If each score is increased by 25%, what are the new mean and standard deviation?
625, 100
if the teacher combines the classes, what will the average final exam score be?
87
many colleges are moving toward coed dormitories. which of the following best describes the directors sampling plan?
A cluster sample
Survey of heads of households in a particular state: which of the following is an incorrect statement about the resulting stratified sample?
A cluster sample would have been more appropriate
department chair person ratings with correlation of r = 1.15 : from this information we can conclude that
A mistake in arithmetic has been made
suppose that the scatterplot of log X and log Y shows a strong positive correlation close to 1. Which of the following is true?
A scatterplot of the variables X and Y shows a strong non-linear pattern
A school psychologist wants to investigate student depression: which of the following best describes the principal's sampling plan?
A stratified random sample
The first Kentucky derby winners: which of the following visual displays is most appropriate?
Bar chart
Boxplot of CO2 levels in 2008 vehicles: What effect, if any, will these changes have on the mean and median CO2 levels?
Both the mean and median will be unchanged.
which country has more children younger than 10 years of age?
Canada
Suppose you wish to compare the average class size of mathematics classes to the average class size of English classes in your high school. Which is the most appropriate technique for gathering the needed data?
Census
The 70 highest dams in the world: List the dams in order of ascending size
Charvak, Grand Coulee, Hoover, Nurek
in a shipment of 100 cartons what is the expected number of broken eggs and what is the standard deviation?
E(broken)= 30 SD (broken) = 1.8
if 50 autos are sold during one month, what is the expected value and standard deviation for the total discounts given?
E(total) = $122,500 SD (total) = $4066
Graph with household income in Laguna Woods, California: What can be said about the ratio (Mean family income/Median family income)?
Greater than one
back to back's templates comparing car battery lives: which of the following are true statements?
I and II
which of the following are true statements? (all are about the histogram of a binomial distribution)
I and III
which of the following statements about residuals from the least squares line are true?
I, II, and III
3 statements, talk about if the population has variance zero: Which of the following are true statements?
II and III
suppose the correlation is negative : given two points from the scatterplot which of the following is possible?
III only ( The first point has a smaller X value and a larger Y value than the second point)
Data on text messages sent by students: What are the corrected IQR and Standard Deviation?
IQR = 71 and and standard deviation = 41.2
Which of the following is an incorrect statement?
In histograms, frequencies can be determined from relative heights
voters of which affiliation were most likely to have no opinion about the amendment?
Independent
When a set of data has suspect outliers which of the following are preferred measures of central tendency and variability
Median and interquartile range
Are "GPA between 2.0 and 3.0" and "skipped classes" independent?
No, because 0.475 is not equal to 0.506
Auto-manufacturer claim about 35 mpg: Does the company's argument seem reasonable given this dotplot?
No, because the possibility of picking 5 cars with an average of 32 mpg or lower from a fleet of cars of known 35 mpg efficiency is very small, only 4 our of 160, or 0.025.
If quartiles Q1 = 20 and Q3 = 30, which of the following must be true?
None are true
A factory dumps tons of pollutants into a river every week. : what is the probability that in a week more than 3 tons are dumped
P (z> 3 - 2.43 —————- 0.88. )
what is the probability that the two randomly selected trailers, one produced by each company, will combine to less than three minutes?
P(z< 180-270 ———— 50. )
Average combined SAT scores: which of the following is a correct conclusion?
Schools with lower percentages of students taking the exam tend to have higher average combined SAT scores.
Multiple gaps and clusters: Which is the best choice to give an overall picture of a distribution?
Stemplot or histogram
Which of the following is a true statement?
Stemplots can show symmetry, gaps, clusters, and outliers
which of the following is a true statement( about normal distributions)
The area under a normal curve is always equal to one, no matter what the mean and standard deviation are
which of the following is a true statement( about the area under the standard normal curve)
The area under the standard normal curve between 0 and 2 is half the area between -2 and 2
Stemplot with ages of CEO's: Which is not a correct statement about this distribution?
The distribution is skewed left and right
1995 Poll about U.S. budget they thought went to foreign aid. (Mean-18 and Median-15) : What do these responses indicate about the likely shape of the distribution of all the responses?
The distribution is skewed to the right
School uniforms by US public schools: which question probably produced which result and why?
The first question probably showed 23% and the second question probably showed 18% because of response bias due to the wording of the questions
Suppose the probability that you will receive an A in AP statistics: which of the following is a proper conclusion?
The given probabilities are impossible
mathematically speaking , casinos and life insurance companies make a profit because of
The law of large numbers
Yearly tuition and fees of all four year colleges: Removing both outliers will effect what changes if any, on the mean and median costs for this state's four year institutions of higher learning?
The median will be unchanged, but the mean will decrease.
which of the following is greatest?
The percentage of those from the west who prefer country
populations P1 and P2 are normally distributed and have identical means. however, the standard deviation of P1 is twice the standard deviation of P2. What can be said about the percentage of observations falling within two standard deviations of the mean for each population?
The percentages are identical
in a western electric company study on the effects of lighting on worker productivity: if it is assumed that the workers new study was in progress, this is an example of?
The placebo effect
rural college windmill: which of the following is a proper and most informative conclusion for an observation with a negative residual?
The predicted noise level is greater than the measured noise level
assuming independence of trading in new car prices for a customer what is the standard deviation of the revenue the dealer should expect to make if a customer trades in a used car and buys a new one?
The square root of 3100^2 PLUS 1200^2 dollars
which of the following statements about the two histograms above is true?
The standard deviation of set B is greater than 5.
Dieticians concerned about teen sugar: Which of the following is a true statement?
The value 60 is an outlier, and there may be others at the high end of the data set
A study is made to determine whether taking AP statistics in high school helps students achieve higher GPAs when they go to college: which of the following is incorrect?
a more meaningful study would be to compare an SRS from each of the two groups of 100 students
which of the following statements are possible, given the graphs?
all three are plausible
some researchers believe that too much iron in the blood can raise the level of cholesterol: is this an experiment or an observational study?
an experiment with a single factor
there are 20 students in an AP statistics class: which of the following is one run of a simulation to estimate the probability of at least one student guesses correctly on over half the questions?
assume "1" is the correct answer and "2,3,4,5" are incorrect answers....
(All about blocking) which of the following is incorrect?
blocking results in increased accuracy because the blocks have smaller size than the original group
which of the following is a true statement?
convenience samples often lead to undercoverage bias.
which of the following is a true statement about the design of matched pair experiments?
each subject might receive both treatments
is hot oatmeal with fruit or a western omelette with home fries in more satisfying breakfast? if the western omelette with home fries receives a substantially higher average score what is a reasonable conclusion?
in general, people find western omelettes with home fries more satisfying for breakfast than hot oatmeal with fruit.
which of the following is greatest?
it is impossible to determine the answer without knowing the actual numbers of people involved
A company employs both men and women in at secretarial and executive positions...: is this possible?
it is possible for both the company report to be true and the investigators claim to be correct.
The number of surveys being conducted over the Internet has been increasing dramatically. : which of the following is NOT true about such surveys?
less undercoverage and non-response bias
what should n be so that the correlation between the X and Y values is one?
no value for N can make r = 1
MLB teams with players names into a hat: Will this method result in a simple random sample of the 750 baseball players?
no, because not each group of 60 players has the same chance of being selected.
opinions of bleacher fans at Wrigley Field: Will this result in a simple random sample of Cub fans who sit in the bleachers?
no, because not every sample of the intended size has an equal chance of being selected
do teenagers preferred sports drinks colored blue or green? : is blinding possible in this experiment?
no, because the volunteers know whether they are drinking a blue or green drink.
suppose you are one of 7 billion people who send in their name for a drawing: is it worth the $0.49 postage it cost you to send in your name?
no, because your expected winnings are only $0.14
in order to minimize response bias, which of these design elements is most important?
pilot testing the survey
what is the equation of the regression line, where facing and back are the winning game proportions when facing the sun and with back to the sun, respectively?
predicted back = 0.056 +920 facing
World ranked chess players: based on this data, what is the resulting linear regression equation?
predicted winnings = 178,000 + 4850 hours
which of the following is a true statement about sampling error?
sampling error concerns natural variation between samples, is always present, and can be described using probability.
in the 1994 issue of parade magazine, the "ask Marilyn" section contain the question: what do you think of Maryland solution of 1.5%?
she assumed independence of events, which is most likely wrong
if the standard deviation of a set of observations is zero you can conclude
that all observations are the same value
A consumer product agency tests miles per gallon for a sample of automobiles using each of four different octanes of gasoline. Which of the following is true?
there are four levels of a single explanatory variable
consider the following three scatterplots: which has the greatest correlation coefficient?
they all have the same correlation coefficient
when the estrogen blocking drug tamoxifen was first introduced : which of the following is a true statement?
this study was an experiment in which the subjects were used as their own controls
adopting common core standards from 50 states: why is stratification used here?
to obtain higher statistical Percision because variability of responses within a state is likely less than variability of responses found in the overall population
in designing an experiment, blocking is used
to reduce variation
average occupancy size of student-rented apartments: is this estimate probably too low or too high?
too high, because of undercoverage bias
consider n pairs of numbers. of the following which could be the least squares line?
y = 6-x
Students in AP statistics class brainteaser time: If the times are all changed to minutes, what will then be the student's standardized score?
z = 2.40