stat exam mock

A professional basketball player is a poor free-throw shooter. Consider situations in which he shoots a pair of free throws. The probability that he makes the first free throw is 0.51. Given that he makes the first, suppose the probability that he makes the second is 0.59. Given that he misses the first, suppose the probability that he makes the second one is 0.36. What is the probability that he makes one of the two free throws? 0.2091 0.1764 0.3855 0.6864

0.3855

In a new split level class, there are 20 undergraduate students and 10 graduate students. The professor is planning on asking two students to complete a long survey about the course in the middle of the semester. If the two students are randomly selected without replacement, what is the probability that one undergraduate and one graduate student are chosen? 0.46 0.56 0.22 0.23 0.44

0.46

Given the probabilities shown below, what is P(A⋂B)? P(A) = 0.65, P(B) = 0.32, and P(B|A) = 0.75 0.208 0.220 0.240 0.4875 Impossible to Determine.

0.4875

1380 randomly sampled registered voters from Tampa, Florida were asked if they thought workers who have illegally entered the US should be (i) allowed to keep their jobs and apply for US citizenship, (ii) allowed to keep their jobs as temporary guest workers but not allowed to apply for US citizenship, or (iii) lose their jobs and have to leave the country. The results of the survey by political ideology are shown below. What percent of these Tampa, Florida voters who identify themselves as conservatives are in favor of the citizenship option? 20.0% 17.0% 6.3% 31.5% 37.1%

20.0%

Suppose you have a data set with the following five-number summary: Minimum = 26, Q1 = 32, Median = 34, Q3 = 38, Maximum = 58. What is the lower cutoff point for potential outliers? (By lower cutoff point, we mean the number such that anything smaller than it is an outlier). 14 23 29 47 56

23

Jim is conducting a health survey of residents of Brazos County. He asks them their age, gender, height (in cm), weight (in kg), type of insurance, marital status, income (in $), and the number of days they were sick in the last month. The possible values for marital status are married, widowed, divorced/separated, single/never married, and living with a partner but not married. How many of the variables in the health survey were categorical and how many were numeric? 6 categorical and 2 numerical. 5 categorical and 3 numerical. 4 categorical and 4 numerical. 3 categorical and 5 numerical. 2 categorical and 6 numerical.

3 categorical and 5 numerical.

The boxplot below shows the distribution of heights of 16 undergraduate statistics students. Using this boxplot, approximately how many students are 69 inches or taller? 4 8 12 16 Impossible to Determine. 25

4

Suppose that you have a bag of 15 spheres and 15 cubes. Each of the shapes contains 4 red, 6 white, and 5 yellow. (So, for example, there are 4 red spheres, 6white spheres, and 5 yellow spheres.) You randomly pick one item from a bag and see that it is a sphere. Then what is the chance that it is a red ball? (Assume you're equally likely to grab a sphere or a cube - they're the same volume.) 4/15 4/30 15/30 8/30

4/15

A researcher is interested in learning how often college students watch TV. They randomly select 500 college students and ask, "In the past seven days, how many days did you watch television?" The random variable X represents the number of days an individual watched television. The probability distribution below shows the results of the survey. What is the expected value of X? x= 0,1,2,3,4,5,6,7 p(x=x) 0.04, 0.03, 0.06, 0.08, 0.09, 0.08, 0.05, 0.57 5.44 5.00 6.00 28.0 3.50

5.44

Below is a histogram of the IQ ("intelligence quotient") scores of 60 fifth-grade students chosen at random from one school. The range is defined as the maximum minus the minimum. What is the range of this distribution?

80

The monthly average high temperatures for New York City have the following five-number summary: the minimum is 40, the median is 63, the third quartile is 77, the interquartile range (IQR) is 32, and the maximum is 84. Which of these shows the correct box-and-whisker plot for the data? A B C D

A

Eli wants to determine whether or not there is an association between gender and GPA among high school seniors in Ohio. He randomly selects 100 high school seniors at Amelia High School, a public school in southwest Ohio. He asks them to report their gender, as well as their current GPA. Out of these 100 students, 57 were female and 43 were male. The average GPA of the 57 female high school seniors was 3.47. What is the population in this study? All high school students. All high school seniors. All high school seniors in Ohio. All high school seniors at Amelia High School. The 100 students were randomly selected to take in the survey.

All high school seniors in Ohio

A state governor wants to survey people in his state to determine their opinions on a particular law up for adoption. He decides to randomly select a few districts in his state and then survey all who live in those districts. Which of the following is a reason why the governor chooses to use a cluster sample? Because they want to learn about each of the different clusters separately. Because it is impossible or not feasible to take a simple random sample or because the governor cannot get a list of every individual in the population. Because they want to use a smaller sample size.

Because it is impossible or not feasible to take a simple random sample or because the governor cannot get a list of every individual in the population.

A researcher wants to determine if a new flu vaccine protects people from the flu better than the current vaccine. He has 100 subjects for his study. He believes that sex will affect how well the vaccine works, so within these 100 subjects, splits them up into males (48 subjects) and females (52 subjects). Within each sex, he randomly assigns half of the subjects to get the new flu vaccine and the other half to get the current flu vaccine. What type of study design is this? Experimental Study: Matched Pairs. Experimental Study: Block Design. Experimental Study: Completely Randomized Experiment. Observational Study: Simple Random Sample. Observational Study: Stratified Random Sample.

Experimental Study: Block Design.

Consider the population of all students at your school. A certain proportion support removing vending machines. Your friend randomly samples 20 students from the​ school and uses the sample proportion who support removing vending machines to predict the population proportion at the school. You take your​ own separate random sample of 20 ​students and find the sample proportion that supports removing vending machines. How likely is it that the sample proportions are the​ same? It is impossible that the sample proportions will be the same because the samples are different. It is very unlikely that the sample proportions will be the same because the samples come from different populations. It is likely that the sample proportions will be the same because the sample represents the same population. It is likely that the sample proportions will be the same because the sample sizes are the same. It is unlikely that the sample proportions will be exactly the same.​ However, they should be close to each other because the samples represent the same population.

It is unlikely that the sample proportions will be exactly the same.​ However, they should be close to each other because the samples represent the same population.

Multiple myeloma is a cancer of the bone marrow currently without an effective cure. It affects primarily older individuals: It is almost never diagnosed in individuals under 40 years old, and its incidence rate (the number of diagnosed malignant cases per 100,000 individuals in the population) is highest among individuals 70years of age and older. If you were to create a histogram to show the distribution of the incidence rate of multiple myeloma by age at diagnosis, how would you describe its skewness? Symmetric. Right Skewed. Left Skewed. Impossible to Determine

Left Skewed

Consider the following measures that can be used to describe a data set: mean, median, IQR, and standard deviation. Which of these following describes all the values that are not robust to outliers? Median and IQR. Median and Standard Deviation. Mean and Standard Deviation. Median and Mean.

Mean and Standard Deviation

For the distribution shown below, which point represents the mean, and which point represents the median? Mean: Point B, Median: Point A. Mean: Point A, Median: Point B. Mean: Point B, Median: Point B. Mean: Point C, Median: Point A. It is impossible to tell from the given information.

Mean: Point B, Median: Point B.

Below is shown a table of IRS income tax returns from 2013 by three income categories, along with whether or not that tax return was audited. Were having an income over $1,000,000 and being audited independent in 2013? Why or why not? No, because 22/393 1413 / 138242. Yes, because 22 0. Yes, because 22 / 393 is neither 0 nor 1. No, because 22/393 0.5. No, because (1413 / 138242) (393 / 138242).

No, because 22/393 1413 / 138242.

Below is shown a table of IRS income tax returns from 2013 by three income categories, along with whether or not that tax return was audited. Were having an income over $1,000,000 and being audited independent in 2013? Why or why not? No, because people with an income over $1 million were much more likely to be audited than everyone else. Yes, because some people with an income over $1 million who were audited, and some weren't. No, because there were some people who both had an income over $1 million and were audited. Yes, because some people made over $1 million, and some didn't, and some people were audited, and some weren't. Answer 4 Toggle editing answer text as HTML No, because the probability that someone made over $1 million doesn't equal the probability that someone was audited. No, because among the people who made an income over $1 million, it's not true that half were audited and half weren't.

No, because people with an income over $1 million were much more likely to be audited than everyone else.

Because of the increasing nuisance of spam email messages, many start-up companies have emerged to develop e-mail filters. One such filter was recently advertised as being 81% accurate. This could mean one of four things. One thing it could mean is that 81% of valid email is allowed through. Let S denote the event that the message is spam and let B denote the event that the filter blocks the message. Which of the following expresses the statement, "81% of valid email is allowed through," as a conditional probability? P(Sc|Bc) = 0.81. P(B|S) = 0.81. P(S|B) = 0.81. P(Bc|Sc) = 0.81. P(Bc|S) = 0.81.

P(Bc|Sc) = 0.81.

Which of the following is an example of a voluntary response sample? Researcher splits their population into a group of males and a separate group of females; she takes a random sample of 25 males and a separate random sample of 25 females. Radio asks people listening to call in and say whether or not they want a new stoplight at a busy intersection. A student asks 15 specific classmates to answer a survey about university fees. Researcher at a major university randomly selects 50 students to participate in a survey. She sends the survey to the 50 selected students via email and 45 of them return the survey.

Radio asks people listening to call in and say whether or not they want a new stoplight at a busy intersection.

A researcher wants to know more about the resting pulse rate of high school-aged children. She takes a random sample of 17 students at a local high school and measures their resting pulse rate. The boxplot below depicts the five-number summary for her data set. Based on this boxplot, what is the skewness of the data set? Symmetric. Left Skewed. Right Skewed. Impossible to Determine

Right Skewed.

Given the following situations, when would you use a histogram? Showing how age and height are related to children in America. Showing the grade distribution of the letter grades on an exam in an introductory statistics class. Showing the distribution of marital status for all of the adults in the United States. Showing how gender and disease status (whether or not someone has a disease) are related. Showing the distribution of the GPA's of all of the students at Texas A&M.

Showing the distribution of the GPA's of all of the students at Texas A&M

Taylor Swift is interested in learning what proportion of her fans watched her premiere Betty live at the ACM Awards on September 16, 2020. She takes a simple random sample of 400 fans and asks them. Of the 400 fans, 382 of them (95.5%) respond that they watched her perform. What is the statistic and what is its value? The statistic is the proportion of all Taylor Swift fans who watched the performance, which is unknown. The statistic is the proportion of all Taylor Swift fans who watched the performance, which is 0.955. The statistic is the proportion of the sampled Taylor Swift fans who watched the performance, which is unknown. The statistic is the group of the Taylor Swift fans who were sampled, which is 400. The statistic is the proportion of the sampled Taylor Swift fans who watched the performance, which is 0.955.

The statistic is the proportion of the sampled Taylor Swift fans who watched the performance, which is 0.955.

A scientist is curious about whether tooth whitening gel actually worked. He randomly assigned 58 adults to use a whitening gel after brushing their teeth, while another 59 adults only brushed their teeth with fluoride toothpaste twice a day. Before the study started and at the end of two weeks of either brushing and using the gel or brushing only, the tooth whiteness was measured, and it was found that the average change in the shade was larger for the gel group. Which of the following can be concluded from the study? There is evidence the gel causes teeth to get whiter, on average. The gel is associated with whiter teeth, but we can't say it was because of the gel. The fact that it was random means the study is biased, so we can't conclude anything. The randomness means that it was a haphazard sample, so there isn't any evidence in this study. While there was random assignment, there wasn't any random selection of participants, so we can't make any conclusions.

There is evidence the gel causes teeth to get whiter, on average

A certain region has a population of 6.5 million. On any given day, the probability that a randomly selected resident decides to visit the amusement park is 1/5000. Assume that each resident's decision to visit is independent of the other residents. What is the probability that all the residents of this region will decide to go to the amusement park tomorrow (assuming the amusement park is open tomorrow)? Exactly equal to zero. Very close to zero. Very close to one. Exactly equal to one. A very large number.

Very close to zero.

A researcher wants to determine if a new exercise program helps people lose weight. She recruits over 1200 subjects (her statistician determined this number from sample size calculations) and randomly assigns them to either participate in the new exercise program or no exercise program. She tells those in the new program group to exercise 3 times a week and tells those in the no exercise group that they should not exercise for the duration of the study. Based on this information, which of the following principles of experimental design is not presented in this study? Randomization. Control/Placebo. Replication/Sample Size. Blinding.

blinding

Which of the following study designs would give you the true value of the parameter? Experiment. Sample Survey. Census. None of the above.

census

Every year, the Higher Education Research Institute at UCLA conducts a large-scale survey of college freshmen on a variety of issues. From the 2013 survey, it was found that 44% of men and 20% of women reported feeling frequently stressed. Which of the following is the most plausible confounding variable that prevents us from concluding that female hormones might cause stressful feelings? number of stressful events experienced. whether or not the student frequently feels stressed. gender. age. whether or not the student was a freshman.

number of stressful events experienced.