ap stats midterms (q&a only)

a jar contains 60 red marblers and 40 white dentato

0.035 (D)

Items produced by a manufacturing process are supposed to weigh 90 grams. The manufacturing process is such, however, that there is variability in the items produced and they do not all weigh exactly 90 grams. The distribution of weights can be approximated by a normal distribution with mean 90 grams and a standard deviation of 1 gram. About what percentage of the items will either weigh less than 87 grams of more than 93 grams? 0.3%

0.3% (B)

A review of voter registration records in a small town yielded the following table of the number of males and females registered as Democrat, Republican, or some other affiliation. Which proportion of males are registered as democrats?

0.30 (D)

Mrs. Bukovac compiled the following table to compare the hand dominance of 200 Cleveland Heights HighSchool students and what methods they prefer using to communicate with their friends.Communication methodCell phone/text In person Online TotalHanddominanceLeft-handed 12 13 9 34Right-handed 43 72 51 166Total 55 85 60 200Suppose one student is chosen randomly from this group of 200. If you know the person that has been randomlyselected is left-handed, what is the probability that they prefer to communicate with friends in person?

0.382 (D)

The area under the standard Normal curve corresponding to z>-1.22 is closest to what value?

0.8888 (E)

A die is loaded so that the number 6 comes up three times as often as any other number. What is the probability of rolling a 1 or a 6?

1/2 (B)

suppose that scores on a certain IQ test are normally distributed with a mean 110 and standard deviation 15. then about 40% of the scores are between what two numbers?

102 and 118 (E)

there are 10 students in mrs. sollom's afternoon stats class. the max point total for the recent quarter was 200 points. the point totals for the 10 students are given in the stemplot below. what is the median point total for this class?

130.5 (B)

a lobster fisherman is keeping track of the productivity of a set of traps he has placed in a favorite location. below are the numbers of lobsters in these traps over the course of 12 different hauls. 0 3 3 3 4 5 5 6 7 7 12 14 according to the outlier rule, which values are outliers?

14 only (B)

Which of the following statements is/are true?I. Correlation and regression require that there are clearly-identified explanatory and response variables.2. Scatterplots require that both variables be quantitative.3. Every least-squares regression line passes through (x, y).

2&3 only (C)

To simulate a toss of a coin we let the digits 0, 1, 2, 3, and 4 correspond to a head and the digits 5, 6, 7, 8, and 9 correspond to a tail. Consider the following game: We are going to toss the coin until we either get a head or we get two tails in a row, whichever comes first. If it takes us one toss to get the head we win $2, if it takes us two tosses we win $1, and if we get two tails in a row we win nothing. Use the following sequence ofrandom digits to simulate this game as many times as possible:12975 13258 45144Use Scenario 5-1. Based on your simulation, the estimated probability of winning nothing is

2/11 (B)

The distribution of the heights of students in a large class is roughly Normal. Moreover, the average height is 68 inches, and approximately 95% of the heights are between 62 and 74 inches.what is the standard deviation of the height distribution?

3 (B)

In a certain town, 60% of the households have fiber optic internet access, 30% have at least one high-definition television, and 20% have both. The proportion of households that have neither fiber optic internet nor high-definition television is:

30% (C)

The following is a histogram showing the actual frequency of the closing prices of a particular stock on the New York Stock Exchange over a 50-day period. What class contains the third quartile?

30-40(C)

a company produces packets of soap powder that are labeled "giant size 32 ounces." the actual weight of soap powder in a box has a normal distribution with a mean of 33 oz and a standard deviation of 0.7 ounces. 95% of packets actually contain more than x ounces of soap powder. what is x

34.15 (D)

If the heights of 99.7% of American men are between 5'0" and 7'0", what is your estimate of the standard deviation of the height of American men?

4 (C)

The five-number summary for the lengths of the first 100 words in Robert Fagles' translation of Homer's Odyssey is 2 3 4 5 12. Which one of the following could be the 60th percentile of this distribution?

4 (C)

the mp3 music files on sharon's computer have a mean size of 4.0 megabytes and a standard deviation of 1.8 megabytes. she wants to create a mix of 10 of the songs for a friend. let the random variable T=the total size (in megabytes) for 10 randomly selected songs from sharon's computer. what is the expected value of T

40 megabytes (D)

You want to take an SRS of 50 of the 816 students who live in a college dormitory. You label the students 001 to 816 in alphabetical order. In the table of random digits you read the entries 96746, 12149, 37823, 71868, 18442, 35119, 62103, 39244. The first three students in your sample have labels...

400, 769, 335 (E)

a worn out bottling machine does not properly apply caps to 5% of the bottles it fills. in a production run of 800 bottles, what is the standard deviation for the number of bottles with improperly applied caps?

6.16 (B)

the 35th percentile of a population is the number x such that

65% of the population scores are above x (B)

a sample of production record for an automobile manufacturer shows the following for production per shift. what is standard deviation

7.07 (B)

the pie chart at right describes the distribution of favorite school subject for 300 high school students. how many students reported that "math" is their favorite subject

78 (C)

the five number summary for the weights (in grams) of 1200 tomatoes rown in a certain greenhouse is 90, 113.5, 140, 161, and 236. how many tomatoes weighed less than 161 grams?

900 (E)

a linear regression equation was computer to predict the final exam score in a stats class fromt eh score on the first test. suppose joe scores 90

91 (A)

A forester who wants to evaluate the health of maple trees in a large forest randomly selects 10 locations in the forest and creates 20-meter diameter circles with each location as a center (making sure none of the circles overlap). he then evaluates all the maple trees in each circle. Which one of the following sampling methods is he using?

cluster sampling (D)

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

Underestimate support for arts programs because of the way the question is worded.( B)

suppose we find the least squares regression line to a set of data. if a plot of the residuals shows a curve pattern

a straight line is not a good summary for the data (A)

a random variable

a variable that takes numerical values that describe the outcomes of a chance process

A sample was taken of the salaries of 20 employees from a large company. The following are the salaries (in thousands of dollars) for this year (the data are ordered). 28 31 34 35 37 41 42 42 42 47 49 51 52 52 60 61 67 72 75 77 Suppose each employee in the company receives a $3000 raise for next year (each employee's salary is increased by $3000). The interquartile range of the salaries will

be unchanged (A)

A sample was taken of the salaries of 20 employees from a large company. The following are the salaries (in thousands of dollars) for this year (the data are ordered). 28 31 34 35 37 41 42 42 42 47 49 51 52 52 60 61 67 72 75 77 Suppose each employee in the company receives a $3000 raise for next year (each employee's salary is increased by $3000). the z scores of the salaries for the employees will

be unchanged (A)

Other things being equal, larger automobile engines are less fuel-efficient. You are planning an experiment to study the effect of engine size on the fuel efficiency of sport utility vehicles. In this study,

gas mileage is a response variable, and you expect to find a negative association (A)

. A sample of production records for an automobile manufacturer shows the following figures for production per shift: 705 700 690 705 what is the standard deviation of this sample?

help

The heights of American men aged 18 to 24 are approximately Normally distributed with a mean of 68 inches and a standard deviation of 2.5 inches. about what percentage of the men are over 70.5 inches tall?

idk

two variables are said to be negatively associated if

larger values of one variable are associated with smaller values of the other (B)

An experiment compares the taste of a new spaghetti sauce with the taste of a successful sauce. Each of a number of tasters tastes both sauces (in random order) and says which tastes better. This is called a...

matched pairs design (D)

the mean weight of pomegranates grown in a certain orchard is 16.5 ounces, with a standard deviation of 3.2 ounces. which of the following best describes the mean and standard deviation of the standardized weights of these pomegranates?

mean = 0 ounces standard deviation = 1 ounce (E)

"least squares" in the term "least squares regression line" refers to

minimizing the sum of the squares of the residuals (D)

You are interested in predicting the cost of heating houses on the basis of how many rooms the house has. A scatterplot of 25 houses reveals a strong linear relationship between these variables, so you calculate a least-squares regression line. "Least-squares" refers to:

minimizing the sum of the squares of the residuals (E)

One hundred 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. The other fifty are given an existing drug for treating severe depression. A psychiatrist evaluates the symptoms of all volunteers after four weeks in order to determine if there has been substantial improvement in the severity of the depression. The study would be double blind if

neither the volunteers nor the psychiatrist knew which treatment any person had received (C)

simple random sampling

none of the above (E)

the height (in feet) and volume (in cubic feet) of usable lumber of 32 cherry trees are measured by a researcher. if data points (65, 70) were removed

r would be larger, because this point does not fall in the pattern of the rest of the data (D)

the letters p, q, r, and s represent probabilities for the four distinct region in the venn diagram below. for each question, indicate which expression describes the probability of the event indicated

r/q+r (D)

which of the following statements about standard deviation is true?

standard deviation measure the typical distance data points in a distribution are from the median (A)

mrs kerns plan to give a math achievement test to samples of 15 year-olds from both the U.S. and Korea in order tocompare mathematics knowledge in the two countries. In each country, you will randomly choose300 students from low-income families400 students from middle-income families200 students from high-income familiesThe sample from Korea is a stratified random sample

stratified random sample (E)

a study of elementary school children. 6-11 finds a high positive correlation between the shoe size x and score y on a test of reading comprehension. the observed association is most likely due to

the effect of another variable, such as age (A)

according the the u.s. bureau of labor statistics, the monthly percentage change in the number of jobs in a certain state for the twelve months of 2011 had a mean of 0.08% and a standard deviation of 1.70%. from this info we can conclude that

the magnitude of the monthly deviations from the mean change averaged about 1.7% (D)

below is a histogram of the heights of gold-medal- winning jumps in the olympic games since 1896. which of the following statements is supported by this histogram?

the median jump is between 80 and 85 inches. (B)

A recent investigation of prices for five-year-old Toyota Camrys in Montgomery, Alabama, and New York, New York, revealed that the mean price in Montgomery was $13,200 with a standard deviation of $1000. In New York, the mean price was $12,800 with a standard deviation of $1800. Which of the following statements is true?

the standard score for a car priced at $15,000 would be higher in montgomery than in new york (C)

the scatter plot below described the relationship between heights of 36 students and the number of words they spelled correctly in spelling bee. what is supported by plot?

the tallest first grader spelled more words correctly than 5 of the 5th graders (D)

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, this 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 an existing medication to the subjects in the other group. forty four percent 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

they can make inferences about cause and effect but not the population (A)

mrs. austin measures the age, marital status and earned income of an SRS of 1463 women. the number and type of variable you have measured is

three; one categorical and two quantitative (E)

Just before the presidential election of 1936, the magazine Literary Digest predicted—incorrectly, as it turned out—that Alf Landon would defeat Franklin Delano Roosevelt. 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

undercoverage (C)

Your friend Albert has invented a game involving two ten-sided dice. One of the dice has threes, fours, and fives on its faces, the other has sixes, eights, and tens. He won't tell you how many of each number there are on the faces, but he does tell you that if X = the result of a single roll of the first die and Y = the result of a single roll of the second die, then μx=3.6, σx=0.8, μy=8.0 and σy=0.9. Let Z = the sum of the two dice when each is rolled once. Here's Albert's game: You give him $10 each time you roll, and he pays you (in dollars) the amount that comes up on the dice. If P = the amount of money you gain each time you roll, the mean and standard deviation of P are:

up=1.60 op=1.20 (C)

which of the following is a method for improving the accuracy of a sample

use large sample sizes (C)

a television station is interested in prediciting whether voters in its viewing area are in favor of offshore drilling. it asks its viewers to phone in and indicate whether they support/ are in favor of or opposed to this practice. of the 2241 viewers who phoned in, 1574 (70%) were opposed to offshore drilling. viewers who phoned in =

voluntary response sample (A)

in a particular games, a fair die is tossed. if the number of spots showing is either 4 or 5 you win $1 , if the number of spots showing is 6 you win $4, and if the number of spots showing is 1,2,or 3 you win nothing. let x=the amount that you win. which of the following is the standard deviation of x

$1.41 (C)

Roll one 8 sided die 10 times. The probability of getting exactly seven sevens in those 10 rolls is given by

(10/7) x (1/8)^7 x (7/8)^3 (B)

a random y has the following distribution what is the value of the constant c

.10 (A)

a researcher wishes to study how the average weight y of kids changes during the first year of life

.3 (A)

mrs. lerch question (breakfast)

.32 (A)

which fo the following statements are true about the least squares regression line

ALL OF THEM(E)

Which of the following is NOT a major principle of good design for all experiments?

BLOCKING (C)

mrs. de la fe, a sportswriter wants to know how strongly orlando residents support the professional baseball team, the orlando rays. she stands outsode and interviews the first 20 ppl this is

D. the 20 people who gave their sportswriter their opinion

a marine biologist wants to estimate the mean size of the barnacle on a stretch of rocky shoreline. to do so, he randomly selected 20, 10 by 10 square inch plots and measured the size of each barnacle this is

cluster sampling (B)

1990 census,

other variables may be confounded with variable x. for xample, states with large populations may have larger numbers of people who don't complete high school and more deaths (C)

the collection of all possible outcomes of a random phenomenon is called

the sample space (D)

A particularly common question in the study of wildlife behavior involves observing contests between "residents" of a particular area and "intruders." In each contest, the "residents" either win or lose the encounter (assuming there are no ties). Observers might record several variables. Which of the following variables is categorical?

whether the "residents" win or lose (C)

Jessica was studying starfish populations and collected starfish of the species 'Pisaster'. She was interested in the distribution of sizes of starfish on a certain shoreline. One measure of size is "arm length". Below is a cumulative frequency distribution for the arm length, in centimeters, of 102 Pisaster individuals. The 'Pisaster' arm length of a particular starfish is 18.20 cm. Is this starfish unusually large?

yes, this star fish is approximately at the 90th percentile for pisaster arm length (C)

a study is conducted to determine if one can predict the yield of a crop based on the amount of fertilizer applied to the soil. the response variable in this study is the

yield of the crop (A)

you are told that your score on an exam is at the 85th percentile of the distribution of scores. which of the following is a correct interpretation of this information

your score was higher than approximately 85% of the people who took this exam (B)