PSU STAT200 QUIZZES 1-6

[Fill in the blank] In an experiment, a person guesses which one of three different cards a researcher has randomly picked (and hidden from the person who guesses). This is repeated four times, replacing the cards each time. Let X = number of correct guesses in the four tries. The probability distribution for X, assuming the person is just guessing, is partially provided above. What is the probability that the person would get 3 or more correct guesses?

0.11

[Fill in the blank] Ellen is taking 4 courses for the semester. She believes that the probability distribution function for X = the number of courses for which she will get an A grade is given above. What is the probability that Ellen will get at least 2 A's?

0.60

[Fill in the blank] Ellen is taking 4 courses for the semester. She believes that the probability distribution function for X = the number of courses for which she will get an A grade is given above. What is the expected number of A's she will get? E(X) = ________ A's

1.75

In Fall 2014, 41.4% of all Penn State University Park graduate and professional degree students were international students. If we were to take a random sample of 100 University Park graduate and professional degrees students from that semester, what is the probability that our sample would be more than 50% international students? [Hint: The standard error of the sample proportion is .04925]

A) .0404

Given that the average height of NBA players is 201 cm with a standard deviation of 8 cm, if we were to take a random sample of 30 NBA players, what is the probability that our sample will have a mean height less than 200 cm? [Hint: The standard error of the mean is 1.461]

A) .2467

The mean weight of babies born at 41 weeks is 3700 grams with a standard deviation of 450 grams. The shape of this distribution is unknown. If a random sample of 80 babies is taken from this population, what is the probability that their sample mean will be less than 3680 grams? [Hint: The standard error of the mean is 50.312]

A) .3453

A pop quiz in a class resulted in the following eight quiz scores: 0, 60, 66, 78, 82, 96, 98, 100. A five-number summary for these test scores is

A) 0, 63, 80, 97, 100.

Based on the 2000 Census, the proportion of the California population aged 15 years old or older who are married is p = 0.524. Suppose n = 1000 persons are to be sampled from this population and the sample proportion of married persons (ρ-hat) is to be calculated. What is the standard deviation of the sampling distribution of ρ-hat?

A) 0.0158

A student doing an internship at a large research firm collected the following data, representing all of the studies the firm had conducted over the past 3 years. What is the probability that the study used randomization, if we already know that the study was a retrospective observational study?

A) 0.1167

The average time taken to complete an exam, X, follows a normal probability distribution with mean = 60 minutes and standard deviation 30 minutes. Using Standard Normal Table, what is the probability that a randomly chosen student will complete the exam in 30 minutes or less?

A) 0.1587

Suppose that a student needs to buy 10 books for her history course. The number of books that she will be able to find used is a binomial random variable X with n = 10 and p = 0.30. In other words, the probability that she will find any given book used is 0.30, and is independent from one book to the next. What is the probability that she will find no more than 2 used books?

A) 0.382

Suppose on a highway with a speed limit of 65 mph, the speed of cars are independent and normally distributed with an average speed = 65 mph and standard deviation = 5 mph. What is the standard deviation for the sample mean speed in a random sample of n = 100 cars?

A) 0.5

According to a 2001 study of college students by Harvard University's School of Public Health, 19.3% of those included in the study abstained from drinking (USA TODAY, April 3, 2002). Suppose that of all current college students in the United States, 20% abstain from drinking. A random sample of four college students is selected with the following binomial results: Binomial with n = 4 and p = 0.2 x P( X = x ) 0 0.4096 1 0.4096 2 0.1536 3 0.0256 4 0.0016 From the table above, what is the probability that at least one student BUT no more than three students in this sample abstain from drinking?

A) 0.5888

Four students' names, including yours, are written on separate slips of paper and placed in a box. The teacher randomly draws two names without replacement. What is the probability that the paper with your name on it will be the second one drawn?

A) 1/4

According to U.S. News and World Report, 18% of World Campus students are 40 years of age or older. If we took a random sample of 200 World Campus students, how many would we expect to be 40 years of age or older?

A) 36

In the population of all test takers, SAT-Math scores are normally distributed with a mean of 500 and standard deviation of 100. If we were to take 100,000 samples of n = 40 individuals who have taken the SAT and compute their sample means, what would we expect the mean of that distribution of sample means to be?

A) 500

Suppose on a highway with a speed limit of 65 mph, the speed of cars are independent and normally distributed with an average speed = 65 mph and standard deviation = 5 mph. What is the expected value of the sample mean speed in a random sample of n = 10 cars?

A) 65 mph

Suppose on a highway with a speed limit of 65 mph, the speed of cars are independent and normally distributed with an average speed = 65 mph and standard deviation = 5 mph. What is the expected value of the sample mean speed in a random sample of n = 100 cars?

A) 65 mph

Three playing cards, without replacement, are chosen at random from a standard 52-card deck. What is the probability of getting an Ace, a King and a Queen in that order?

A) 8/16575

For which of the following situations would the Rule for Sample Proportions (i.e. we could say that the sample proportion distribution approximates a normal distribution) not apply?

A) A random sample of 100 is taken from a population in which the proportion with the trait of interest is 0.98.

For which of the following situations would the Central Limit Theorem not apply?

A) A random sample of size 20 is drawn from a skewed population.

Which one of the following variables is not categorical? A) Age of a person. B) Gender of a person: male or female. C) Choice on a test item: true or false. D) Marital status of a person (single, married, divorced, other)

A) Age of a person.

Close all minitab files Click the following link Minitab Data or Excel Data. From this data, use software to answer the following: 1. How many students answered the question regarding SAT Math scores (Column C14)? 2. Which Gender reported having the higher mean GPA (column C2)?

A) Answered = 241; Higher Mean GPA = Female;

For the given situation, decide if the random variable described is a discrete random variable or a continuous random variable. Random variable X = the number of letters in a word picked at random out of the dictionary.

A) Discrete random variable

A six-sided die is made that has four Green sides and two Red sides, all equally likely to land face up when the die is tossed. The die is tossed three times. Which of these sequences (in the order shown) has the highest probability?

A) Green, Green, Green

According to a recent Gallup poll, about 60% of all American adults owned a cell phone at the time of the poll. The results are based on telephone interviews with a randomly selected national sample of 998 adults, 18 years and older, conducted March 30-April 2, 2001. The 95% margin of error was reported to be 3.5%. Which of the following statements correctly interprets the reported margin of error of 3.5%?

A) In about 95% of all random samples of this size from the same population, the difference between the sample percent and the population percent will be less than 3.5%.

Which of the following best describes the standardized (z) score for an observation?

A) It is the number of standard deviations the observation falls from the mean.

Click the following link Minitab Data or Excel Data. From this data, use software to answer the following: 1. The mean of the variable Height in column C6. 2. The Interquartile Range (IQR) of the variable GPA in column C2. 3. Describe the shape of the variable CellTime in column C5

A) Mean = 67.777; IQR = 0.62 ; Skewed right

The above histogram is for the weights (lbs) of 63 male college students. (Source: idealwtmen dataset on the CD.) What is the approximate shape of the distribution?

A) Nearly symmetric.

Which of the following is the best example of a population from which a cluster sample would be easier to obtain that a simple random sample?

A) Passengers who will be flying in the upcoming week on a certain airline.

A group of middle school students are conducting a study of running speed. They take a sample of 30 middle school students and time how long it takes them to run 40 meters. Which of the following graphical representations is most appropriate for use with this data?

A) Single boxplot

Is the given percent a statistic or a parameter? A customs inspector sampled 5 boxes among 20 boxes being shipped from out of the country. He found that one of the five boxes (20%) contained an illegal food item.

A) Statistic

A special education teacher was interested in examining the effect of giving gifted students online instruction as opposed to instruction in a traditional classroom. She had a sample of 10 gifted students. She used a random number generator to assign each student a number. Students with even numbers were assigned to stay in the traditional classroom. Students with odd numbers were assigned to take online courses. At the end of one semester she found that students in the online group had greater gains in demonstrated knowledge. Which of the following is true about this study?

A) The study lacks replication.

Which one of these variables is a continuous random variable? A) The time it takes a randomly selected student to complete an exam. B) The number of tattoos a randomly selected person has. C) The number of women taller than 68 inches in a random sample of 5 women. D) The number of correct guesses on a multiple choice test.

A) The time it takes a randomly selected student to complete an exam.

What is the mode according to this chart?

A) Thin Mints

For the following statement, determine if it is true or false. If events D and E are known to be mutually exclusive, then P(D|E) = 0.

A) True

A newspaper reported that there is a positive relationship between daily ice cream sales and homicide rates. A reader wrote the paper to point out that both ice cream sales and homicide rates are likely related to the outdoor temperature. In the original newspaper article, outdoor temperature was

A) a lurking variable.

A thumbtack is tossed repeatedly and observed to see if the point lands resting on the floor or sticking up in the air. The goal is to estimate the probability that a thumbtack would land with the point up. That probability is an example of

A) a relative frequency probability based on long-run observation.

A researcher is conducting a study of World Campus students to better understand the variables related to degree completion. A survey is given to World Campus students and the first question is "Which of the following best describes your gender? (1) man, (2) woman, (3) transgendered, (4) other, (5) prefer not to answer" In this scenario, gender is a

A) categorical variable.

A statistics class has 4 teaching assistants (TAs): three female assistants (Lauren, Rona, and Leila) and one male assistant (Josh). Each TA teaches one discussion section. Two students, Bill and Tom, who don't know each other, each pick a discussion section. The two events B = {Bill's TA is Lauren} and T = {Tom's TA is a woman} are

A) independent events.

Statistic is to sample as parameter is to

A) population.

Decide if the probability described is a subjective (personal) probability or a relative frequency probability: A recent college graduate claims he only has a 30% chance of finding a job in the next two months. The chance of 30% is a

A) subjective probability.

According to a recent Gallup poll, about 60% of all American adults owned a cell phone at the time of the poll. The results are based on telephone interviews with a randomly selected national sample of 998 adults, 18 years and older, conducted March 30-April 2, 2001. The margin of error was reported to be 3.5%. What was the population of interest in this Gallup Poll?

All American Adults

Suppose that vehicle speeds at an interstate location have a normal distribution with a mean equal to 70 mph and standard deviation equal to 8 mph. What is the z-score for a speed of 64 mph?

B) -0.75

The time taken for a computer to boot up, X, follows a normal distribution with mean 30 seconds and standard deviation 5 seconds. What is the standardized score (z-score) for a boot-up time of x =30 seconds?

B) 0.0

Based on the 2000 Census, 31.8% of grandparents in California are the primary caregivers for their grandchildren. Suppose n = 1000 persons are to be sampled from this population and the sample proportion of grandparents as primary caregivers (ρ-hat) is to be calculated. What is the standard deviation of the sampling distribution of ρ-hat?

B) 0.0147

Sleep apnea is a condition involving irregular breathing during sleep. Suppose that about 20% of a random sample of n = 64 men experience sleep apnea. What is the standard error of the sample proportion?

B) 0.05

Suppose that a student needs to buy 8 books for her history course. The number of books that she will be able to find used is a binomial random variable X with n = 8 and p = 0.30. In other words, the probability that she will find any given book used is 0.30, and is independent from one book to the next. What is the probability that she will find exactly 3 used books?

B) 0.254

The average time taken to complete an exam, X, follows a normal probability distribution with mean = 60 minutes and standard deviation 30 minutes. Using Standard Normal Table, what is the probability that a randomly chosen student will take at least an hour to complete the exam?

B) 0.5000

Use software to answer the following: You just found out that you have been kicked out of your apartment (through no fault of your own!) and need to find a new place to live. Suppose monthly rent for an individual is a normally distributed random variable with a mean of 334 dollars and a standard deviation of 22 dollars. What is the probability that you will find an apartment that costs less than 350 dollars per month.

B) 0.766471

Scores on an achievement test averaged 70 with a standard deviation of 10. Serena's score was 85. What was her standardized score (also called a z-score)?

B) 1.5

Every student taking elementary statistics at a large university (about 1,100 students) participated in a class project by rolling a 6-sided die 100 times. Each individual student determined the proportion of his or her 100 rolls for which the result was a "1". The instructor plans to draw a histogram of the 1,100 sample proportions. What will be the approximate mean for the 1,100 sample proportions?

B) 1/6

A five number summary for hours studied in a week were 5, 12, 14, 18, and 20. What is the value such that 75% of the students studied longer than that value?

B) 12 hours

A child is observing squirrels in the park and notices that some are black and some are gray. For the next five squirrels she sees, she counts X = the number of black squirrels. Suppose X is a binomial random variable with n = 5 and p = 0.50. What is the expected number of black squirrels she will see, E(X)?

B) 2.5

According to the Penn State Fact Book for Enrollment by Ethnicity Fall 2005 [University Park], roughly 4 out of 5 students enrolled are White. What is the probability that a student who was enrolled last Fall at University Park was non-White?

B) 20%

In a given sample, gender and coffee consumption are independent. If 65% of the sample is men and 80% consume coffee, what percentage of the overall sample are men who drink coffee?

B) 52%

If one card is randomly picked from a standard deck of 52 cards, the probability that the card will be a red suit (Heart or Diamond), or a face card (Jack, Queen, or King), or both, is

B) 61.5% (32/52)

For the given situation, decide if the random variable described is a discrete random variable or a continuous random variable. Random variable X = the time (in seconds) it takes one email to travel between a sender and receiver.

B) Continuous random variable

For the given situation, decide if the random variable described is a discrete random variable or a continuous random variable. Random variable X = the weight (in pounds) a dieter will lose after following a two week weight loss program.

B) Continuous random variable

A student doing an internship at a large research firm collected the following data, representing all of the studies the firm had conducted over the past 3 years. Define the events E = {the study was an experiment}, U = {the study used randomization} and R = {the study was a retrospective observational study}. Which of the following sets of events are disjoint?

B) E and R

For the following statement, determine if it is true or false. If events A and B are known to be independent and P(A) = 0.2 and P(B) = 0.3, then P(A and B) = 0.5.

B) False

Correctly identify whether the following situations satisfy the conditions required to conduct a Binomial experiment. Selecting a few voters from a very large population of voters and observing whether or not each of them favors a certain proposition in an election when 54% of all voters are known to be in favor of this proposition.

B) NOT Binomial

If the probability that it will rain today is .45, what is the probability that it will not rain today?

B) P (not rain) = .55

Is the given percent a statistic or a parameter? 75% of all students at a school are in favor of more bicycle parking spaces on campus.

B) Parameter

What is this graph highlighting?

B) The median

Which of the following is an example of a binomial random variable? A) The number of games your favorite baseball team will win this coming season. B) The number of questions you would get correct on a 15 question true-false test if you randomly guessed on all questions. C) The number of siblings a randomly selected student has. D) The number of coins a randomly selected student is carrying.

B) The number of questions you would get correct on a 15 question true-false test if you randomly guessed on all questions.

Which of the following statements is true about a parameter and a statistic for samples taken from the same population?

B) The value of the statistic varies from sample to sample.

Which statement is true about x-bar and ρ-hat?

B) They are both statistics.

An educational researcher is comparing the time management skills of students enrolled at Penn State World Campus and Penn State University Park. She knows that there are more traditional students enrolled through University Park and more adult students enrolled through World Campus. Previous research has shown that there is a relationship between age and time management skills, so the researcher includes age in her study. This this study, age is

B) a confounding variable.

The pie chart above shows the amounts of energy produced by all sources in the United States during the year 2000. The combined percent of oil and gas was

B) between 25% and 50% of the total energy.

A statistics class has 4 teaching assistants (TAs): three female assistants (Lauren, Rona, and Leila) and one male assistant (Josh). Each TA teaches one discussion section. A student picks a discussion section. The two events W = {the TA is a woman} and M = {the TA is a man} are

B) disjoint (mutually exclusive) events.

Decide if the probability described is a subjective (personal) probability or a relative frequency probability: In a sample of 1000 students majoring in the humanities, 660 were female. The 66% (660/1000) chance of a humanities major being female is a

B) relative frequency probability.

A survey-taker randomly selected 1000 students who were studying in the library and found that 90% of these students were in favor of longer library hours. The results of this study, if applied to all students in the university, are questionable because of

B) selection bias.

A population of taxpayers is divided into five income levels and a simple random sample is selected from each one for an audit. This is an example of a _________ sample.

B) stratified

Olivia wants to learn a foreign language. To get an idea of how satisfied other students were after taking a foreign language course, she decides to take a random sample of 20 students. If Olivia randomly selects 5 students from French, 5 from German, 5 from Spanish, and 5 from Chinese, the sampling method is a

B) stratified random sample.

A national research firm was studying the amount of money spent by Americans on coffee on a weekly basis in various regions of the United States. They took a random sample of 5,000 Americans from each region and asked how much they spent on coffee each week. They found that on average individuals from the northeast spend more money on coffee than individuals from any other region of the United States. We cannot say that living in the northeast causes people to spend more money on coffee (i.e., we cannot make a cause-and-effect conclusion) because

B) this study lacks random assignment.

A soft drink company holds a contest in which a prize may be revealed on the inside of the bottle cap. The probability that each bottle cap reveals a prize is 0.2 and winning is independent from one bottle to the next. What is the probability that a customer must open three or more bottles before winning a prize?

C) (0.8)(0.8) = 0.64

Heights of college women have a distribution that can be approximated by a normal curve with a mean of 65 inches and a standard deviation equal to 3 inches. Using Standard Normal Table, about what proportion of college women are between 65 and 68 inches tall?

C) 0.3413

Weights of females have approximately a normal distribution with mean 135 lbs. and standard deviation 20 lbs. Allison weighs 145 lbs. What is the z-score for her weight?

C) 0.50

Using Standard Normal Table, what is the probability that Z is between -1 and 1, P(-1 < Z < 1)?

C) 0.6826

Use software to answer the following: You just found out that you have been kicked out of your apartment (through no fault of your own!) and need to find a new place to live. Suppose monthly rent for an individual is a normally distributed random variable with a mean of 334 dollars and a standard deviation of 22 dollars. What is the probability that you will find an apartment that costs less than 400 dollars per month.

C) 0.998650

Heights for a sample of n = 4 women are measured. For the sample, the mean is 64 inches and the standard deviation is 3 inches. What is the standard error of the mean?

C) 1.5

A five number summary for hours studied in a week were 5, 12, 14, 18, and 20. What is the value such that 50% of the students studied longer than that value?

C) 14 hours

A standard 52-card deck is shuffled and 2 cards are picked, without replacement, from the top of the deck. The probability that the first card is a face card (Jack, Queen, King) and the second card is not a face card is

C) 18.1%

The mean hours of sleep that students get per night is 7 hours, the standard deviation of hours of sleep is 1.7 hours, and the distribution is approximately normal. Complete the following sentence. For about 95% of students, nightly amount of sleep is between ______.

C) 3.6 and 10.4 hrs

The probability distribution shown above is for the random variable X = number of classes for which full time students at a university are enrolled in a semester. What is the expected value of courses taken per student?

C) 5.2

A standard 52-card deck is shuffled and 2 cards are picked, without replacement, from the top of the deck. The probability that the both cards are Hearts is

C) 5.88%

In a survey, students are asked how many hours they study in a typical week. A five-number summary of the responses is: 2, 9, 14, 20, 60. Which interval describes the number of hours spent studying in a typical week for about 50% of the students sampled?

C) 9 to 20

For a large sample of blood pressure values, the mean is 120 and the standard deviation is 10. Assuming a bell-shaped curve, which interval is likely to be about the interval from the minimum to maximum blood pressures in the sample?

C) 90 to 150

In the past five years, only 5% of pre-school children did not improve their swimming skills after taking a Beginner Swimmer Class at a certain Recreation Center. What is the probability that a pre-school child who is taking this swim class will improve his/her swimming skills?

C) 95%

Every student taking elementary statistics at a large university (about 1,100 students) participated in a class project by rolling a 6-sided die 100 times. Each individual student determined the proportion of his or her 100 rolls for which the result was a "1". The instructor plans to draw a histogram of the 1,100 sample proportions. What will be the approximate shape of this histogram?

C) Normal (bell-shaped)

Suppose that for X = net amount won or lost in a lottery game, the expected value is E(X) = -$0.50. What is the correct interpretation of this value?

C) Over a large number of plays the average outcome for plays is a net loss of 50 cents.

Which of the following would indicate that a dataset is skewed to the right?

C) The mean is much larger than the median.

Which of the following would indicate that a dataset is not bell-shaped?

C) The mean is much smaller than the median.

A student is randomly selected from a large college. Define the events C = {the student owns a cell phone} and I = {the student owns an iPod}. Which of the following is the correct interpretation of the probability P(I|C)?

C) The proportion of students who own a cell phone who also own an iPod.

A survey was given to sophomores at a university and one of the questions asked was "What is the probability that you will leave school before you graduate?" The answer to this question for an individual student is an example of

C) a personal probability.

Olivia wants to learn a foreign language. To get an idea of how satisfied other students were after taking a foreign language course, she decides to take a random sample of 20 students. If Olivia randomly selects one class among all the foreign language classes taught that year, and then interviews all students in that class, the sampling method is a

C) cluster sample.

This distribution of final scores is

C) left skewed.

For a survey of American diets a random sample of 1000 people were contacted. Of the 1000 people, 340 people completed the questionnaire. The results of this study, if applied to all Americans, are questionable because of

C) nonresponse bias.

When a representative sample is selected but only a small proportion contacted actually participate in the study, the problem is called

C) nonresponse bias.

Sara is a frequent business traveler. For security purposes, 10% of all people boarding airplanes are randomly selected for additional screening just prior to boarding. What is the probability that the first time Sara is selected for screening is on her third flight?

D) (0.9)(0.9)(0.1)

In a gambling game, on every play, there is a 0.1 probability that you win $7 and a 0.9 probability that you lose $1. What is the expected value of this game?

D) -$0.20

A medical treatment has a success rate of 0.8. Two patients will be treated with this treatment. Assuming the results are independent for the two patients, what is the probability that neither one of them will be successfully cured?

D) 0.04

Based on her past experience, a professor knows that the probability distribution for X = number of students who come to her office hours on Wednesday is given above. What is the probability that at least 1 student comes to office hours on Wednesday?

D) 0.90

According to a 2001 study of college students by Harvard University's School of Public Health, 19.3% of those included in the study abstained from drinking (USA TODAY, April 3, 2002). Suppose that of all current college students in the United States, 20% abstain from drinking. A random sample of four college students is selected with the following binomial results: Binomial with n = 4 and p = 0.2 x P( X = x ) 0 0.4096 1 0.4096 2 0.1536 3 0.0256 4 0.0016 From the table above, What is the probability that at most two college students in this sample abstain from drinking?

D) 0.9728

Using Standard Normal Table, what is the probability that Z is less than or equal to 2, P(Z ≤ 2)?

D) 0.9772

Suppose two different states each pick a two-digit lottery number between 00 and 99 (for a 100 possible numbers). What is the probability that both states pick the number 13?

D) 1/10,000

A card is drawn at random from a standard 52-card deck. The conditional probability that the card is a 2 given that a 2 or a 3 was drawn is

D) 50.0% (1/2)

In this distribution, which of the following heights is an outlier?

D) 76 inches

Lauren wants to wear something warm when she leaves for class. She reaches into her coat closet without looking and grabs a hanger. Based on what she has in her coat closet, she has a 30% chance of picking a sweater, a 50% chance of picking a coat, and a 20% chance of picking a jacket. What is the probability that she will pick a sweater or a coat?

D) 80%

Which of the following statements best describes the relationship between a parameter and a statistic?

D) A statistic is used to estimate a parameter.

Which of the following is not a term used for a quantitative variable?

D) Categorical variable

Which of the following is not true about drawing a simple random sample from a population?

D) It requires that the size of the sample be no more than 5% of the size of the population.

Which statistic is not resistant to an outlier in the data? A) Lower quartile B) Upper quartile C) Median D) Mean

D) Mean

Students who live in the dorms at a college get free T.V. service in their rooms, but only receive 6 stations. On a certain evening, a student wants to watch T.V. and the six stations are broadcasting separate shows on baseball, football, basketball, local news, national news, and international news. The student is too tired to check which channels the shows are playing on, so the student picks a channel at random. The two events F = {the student watches football} and A = {the student watches an athletic event} are

D) None of the above.

Which one of these variables is a categorical variable? A) Number of ear pierces a person has B) Height of a person C) Weight of a person D) Opinion about legalization of marijuana

D) Opinion about legalization of marijuana

The above boxplot is for the results of the women's 400-meter dash final race during the 2000 Olympics in Sydney, Australia. Cathy Freeman won in 49.11 seconds. Choose the correct statement about the boxplot.

D) The slowest time of 51.04 seconds is an outlier.

A pharmaceutical company is testing the effectiveness of a new non-steroidal anti-inflammatory drug at treating back pain. They take a sample of 8,000 individuals with back pain. Half are randomly assigned to receive the new drug and half are randomly assigned to receive no treatment. The group that received the new drug reported less pain than the group that received no drug. Which of the following is true about this study?

D) The study lacks a placebo group.

Which of the following statements is correct about a parameter and a statistic associated with repeated random samples of the same size from the same population?

D) Values of a statistic will vary according to the sampling distribution for that statistic.

If the size of a sample randomly selected sample from a population is increased from n = 100 to n = 400, then the standard deviation of ρ-hat will

D) decrease by a factor of 2.

A magazine printed a survey in its monthly issue and asked readers to fill it out and send it in. Over 1000 readers did so. This type of sample is called a

D) self-selected sample.

Use software to answer the following: You just found out that you have been kicked out of your apartment (through no fault of your own!) and need to find a new place to live. Suppose monthly rent for an individual is a normally distributed random variable with a mean of 334 dollars and a standard deviation of 22 dollars. What is the probability that you will find an apartment that costs more than 300 dollars per month.

E) 0.938882

According to a recent Gallup poll, about 60% of all American adults owned a cell phone at the time of the poll. The results are based on telephone interviews with a randomly selected national sample of 998 adults, 18 years and older, conducted March 30-April 2, 2001. The 95% margin of error was reported to be 3.5%. Which of the following statements correctly interprets the reported margin of error of 3.5%?

In about 95% of all random samples of this size from the same population, the difference between the sample percent and the population percent will be less than 3.5%.

A randomly selected sample of 1,000 college students was asked whether they had ever used the drug Ecstasy. Sixteen percent (16% or 0.16) of the 1,000 students surveyed said they had. Which one of the following statements about the number, 0.16 is correct?

It is a sample proportion

Decide if the sample is representative (or not) of the population for the question of interest. Question: Average daily hours of sleep over a one year period. Sample: Hours of sleep for 100 randomly selected students the night before an exam. Population: All students in the university.

Not representative

Decide if this study is experimental or observational.

Observational

Decide if this study is experimental or observational. A survey asked 100 Americans how many cups of coffee they drink in a typical week. They computed the average to be 14.7 cups per week.

Observational

When a representative sample is selected but only a small proportion contacted actually participate in the study, the problem is called

non responsive bias

If the target population is all U.S. adults, then a telephone directory would not make a good sampling frame because

people with unlisted numbers or not phones are not included

When the method for selecting subjects produces a sample that does not represent the population of interest, the problem is called

selection bias