AP Stats Chp 1, 2, and 4 Multiple Choice

The stemplot below shows the number of home runs hit in 2008 by members of the Philadelphia Phillies, who won major League Baseball's World Series that year. (Each of the 13 players who appeared in at least half of the Phillie's games that year is included). Note that 4/8 = 48 home runs What is the five number summary of this data

0, 6.5, 11, 28.5, 48

Birthweights at a local hospital have a Normal distribution with a mean of 110 oz. and a standard deviation of 15 oz. The proportion of infants with birthweights between 125 oz. and 140 oz. is about

A. 0.136

A set of data has the following five-number summary: minimum=5, first quartile=40, median=52, third quartile=60, maximum=93

A. 4,8,98

A survey typically records many variables of interest to the researches involved. Below are some of the variables from a survey conducted by the U.S. Postal Service. Which of the variables is categorical?

A. county of residence

You want to use numerical summaries to describe a distribution that is strongly skewed to the left. Which combination of measure of center and spread would be the best ones to use?

A. median and interquartile range

The standard deviation of 16 peoples' weights (in pounds) is computed to be 5.4. The variance of these measurements is

B. 29.16

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

B. 65% of the population scores are above x

The time to complete a standardized exam is approximately Normal with a mean of 70 minutes and a standard deviation of 10 minutes. How much time should be given to complete the exam so that 80% of the students will complete the exam in the time given?

B. 78.4 minutes

Jack and Jill are both enthusiastic players of a certain computer game. Over the past year, Jack's mean score when playing the game is 12,400 with a standard deviation of 1500. During the same period, Jill's mean score is 14,200, with a standard deviation of 2000. They devise a fair contest: each one will play the game once, and they will compare z-scores. Jack gets a score of 14,000, and Jill gets a score of 16,000. Who won the contest, and what are their z-scores?

B. Jack's z=1.07; Jill's z=0.90; jack wins the contest

We wish to choose a simple random sample of size three from the following employees of a small company. To do this, we will use the numerical labels attached to the names below. Use Scenario 4-3. The simple random sample is

C. Bechhofer, Taylor, Weiss

A researcher reports that the participants in his study lost a mean of 10.4 pounds after two months on his new diet. A friend of yours comments that she tried the diet for two months and lost no weight, so clearly the report was a fraud. Which of the following statements is correct?

D. The report gives only the mean. This does not imply that all participants in the study lost 10.4 pounds or even that all lost weight. Your friend's experience does not necessarily contradict the study results.

A sample of 99 distances as a mean of 24 feet and a median of 24.5 feet. Unfortunately, it has just been discovered that the maximum value in the distribution, which was erroneously recorded as 40, actually had a value of 50. If we make this correction to the data, then

D. the median remains the same, the mean is increased

A sample of 250 high school students were asked, "If you had $1000 to contribute to one kind of charitable organization, which type of organization would you choose? Below is a two-way table of responses to this question and gender.

D. the proportion of males who said they would contribute to an environmental organization was higher than the proportion of females who said they would contribute such an organization

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. The class that contains the third quartile is

E. 30-40

Which of the following dot plots would be best approximated by a Normal Distribution

E. E

The weights of the male and female students in a class are summarized in the following boxplots

E. the male students have less variability than the female students

when a basketball player makes a pass to a teammate who then scores, he earns an "assist." Below is a Normal probability plot for the number of assists earned by all players in the National Basketball Association during the 2010 regular season. Which of the follwing statements about the shape of this distribution is true?

The distribution is skewed.

Scenario 4-8. Researches 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, the 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 perfect 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. Use Scenario 4-8. Which of the following best describes the inferences the researchers can make based in his results?

They can make inferences about both cause and effect and the populations from which the samples were taken.

A television station is interested in predicting 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 are opposed to this practice. Of the 2241 viewers who phoned in, 1574 (70%) were opposed to offshore drilling. The viewers who phoned in are

a voluntary response sample

Does caffeine improve exam performance? Suppose all students in the 8:30 section of a course are given a "treatment" (two cups of coffee) and all students in the 9:30 section are not permitted to have any caffeine before a mid-term exam. Use Scenario 4-6. Unfortunately, any systematic difference between the two sections on the exam might be due to the fact that the 8:30 and 9:30 classes have different instructors. This is an example of

confounding

The principle reason for the use of random assignment in designing experiments is that it

creates approximately equal groups for comparison

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

matched pairs design

The normal curve below describes the death rates per 100,000 people in developed countries in the 1900's The mean and standard deviation of this distribution are approximately

mean = 190 ; standard deviation = 65

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 ad recieved

The Bradley Effect is a theory proposed to explain observed discrepancies between voter opinion polls and election outcomes in a some elections where a white candidate and a non-white candidate run against each other. The theory proposes that some voters tend to tell pollsters that they are undecided or likely to vote for a non-white candidate, and yet, on election day, vote for the white opponent. This is an example of

response bias

In an experiment, an observed effect so large that it would rarely occur by chance is called

statistically significant

A large university is considering introducing a new major in Economic Geography and wishes to poll the current student body for their opinion of the feasibility of introducing such a major. The Office to Public Relations mails a questionnaire on this issue to a SRS of 2000 students currently enrolled in the university. Of the 2000 questionnaires mailed, 532 have been returned of which 219 students support the new major. Which of the following represents the population for this study

the 2000 students selected represent a sample of the population of all currently enrolled students

Two studies are run to compare the experiences of low-income families receiving food stamps to those receiving cash subsides. The first study interviews 50 families who have been in each government program for at least 2 years, while the second randomly assigns 50 families to each program and interviews them after 2 years. Which of the following is a true statement?

the first study is an observational study; the second is an experiment

In the late 1990's Scotland was considering independence from England. An opinion poll showed that 51% of Scots favor "independence." Another poll taken at the same time showed that only 34% favored being "separate" from England. The reason these results differ by so much is that.

the wording of questions has a big effect on poll results

Twelve people who suffer from chronic fatigue syndrome volunteer to take part in an experiment to see if shark fin extract will increase one's energy level. Eight of the volunteers are men, and four are women. Half of the volunteers are to be given shark fin extract twice a day, and the other half are to be given a placebo twice a day. We wish to make sure that four men and two women are assigned to each of the treatments, so we decide to use a block design with the men forming one block and the women the other. A block design is appropriate in this experiment if

we believe men and women will respond differently to treatments

use Scenario 2-1. The mean salary for the employees will

B. increase by $3,000

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 or more than 93 grams.

0.3%