stats 10 midterm 1

pdf

School

University of California, Los Angeles *

*We aren’t endorsed by this school

Course

Subject

Statistics

Date

Feb 20, 2024

Type

pdf

Pages

Uploaded by ChefComputer2192

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 1/22  This quiz has been regraded; your new score reflects 2 questions that were affected. Exam 1 Due Feb 4 at 11:59pm Points 30 Questions 26 Available Feb 2 at 8am - Feb 6 at 11:59pm 5 days Time Limit None Allowed Attempts Unlimited Instructions This quiz was locked Feb 6 at 11:59pm. Attempt History Attempt Time Score Regraded LATEST Attempt 1 77 minutes 28.67 out of 30 29.67 out of 30 Score for this attempt: 29.67 out of 30 Submitted Feb 2 at 2:12pm This attempt took 77 minutes. Here is some general information that may be helpful in using Canvas Quizzes. When you are done answering the questions and are ready to submit your answers for grading, click Submit Quiz . If you experience a technical problem that interferes with your ability to complete a quiz during the specified time, save a record of the issue if possible and email your instructor (bingling.wang@stat.ucla.edu) as soon as possible—you don't have to wait until the quiz has closed.  General Quiz Information 1 / 1 pts Question 1 Each year, 19 million U.S. adults are affected by clinical depression. The following table shows data from a study on 109 clinically depressed individuals.

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 2/22 Hospital : The patient’s hospital, represented by numbers (1-6) Treatment : The treatment received by the patient Outcome : Whether a recurrence occurred during the patient’s treatment Time : Either the time in days until the first recurrence or, if a recurrence did not occur, the length in days of the patient’s participation in the study Acute Time : The time in days that the patient was depressed prior to the study Age : The age of the patient in years when the patient entered the study Gender : The patient’s gender Which of the following is true about the data? (Select all that apply) There are four numerical variables in the data set. The sample size of the data is 109. Correct! Correct! There are seven variables in the data. Correct! Correct! Some categorical variables are coded as numerical values. Correct! Correct! Your answer is correct. 1 / 1 pts Question 2 Which of the following is a type of nominal variable? (Select all that apply)

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 3/22 Car Condition (Excellent, Good, Fair, Poor) Political Affiliation (Democrat, Republican, Independent) Correct! Correct! Stage of cancer: Stage I, II, III, or IV Social Security Numbers Correct! Correct! Education level: high school, BS, MS, PhD Your answer is correct. 1 / 1 pts Question 3 A researcher wants to find out the effect of using colored paper on students' memory. She randomly divides a sample of students into two groups. One group will take a memory test printed on colored paper, and the other group will take the same memory test printed on plain white paper. This is an observational study because the researcher observes only the results of the memory test. This is a controlled experiment because the students were randomly assigned to two groups by the researcher. Correct! Correct!

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 4/22 This is a controlled experiment because the students chose whether they want to use colored paper or white paper. This is an observational study because the students chose whether they want to use colored paper or white paper. 1 / 1 pts Question 4 A researcher wants to find out the effect of tutoring on students' grades in a statistics class. Free tutoring was provided for students who want it. Then she compared the final grades for the students that took advantage of the tutoring and the students that did not. Identify the type of study. This is an observational study because the students' final grades can be observed. This is an experimental study because the students choose whether they want tutoring or not. This is an observational study. The researchers do not assign students to receive tutoring or not. Correct! Correct! This is an experimental study because the students were assigned to get tutoring by the researcher. 1 / 1 pts Question 5

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 5/22 A study took a random sample of 1000 people and examined their social media habits. Each person was classified as either a light, moderate, or heavy social media user depending on how much time he or she spends on social media every day. The researchers then looked at which groups tended to be happier, and the study showed that the people in the light user group tend to be happier than those in the moderate or heavy user group. Can the researchers make causal conclusions from the study? Yes, because the sample size is large. Yes, because it used a random sample. Not necessarily, because it randomly assigned 1000 people in different groups. Not necessarily, because it is an observational study. Correct! Correct! Original Score: 1 / 1 pts Regraded Score: 1 / 1 pts Question 6  This question has been regraded. A book store owner collected data on the number of customers who purchase a book by a certain author. Data set: 1, 3, 4, 4, 5, 6, 7, 2, 3, 4, 4, 5, 6, 8, 2, 3, 4, 5, 6, 7, 9 Which of the following description is correct?

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 6/22 On five of the twenty one days observed by the book store owner, there were four books by the author purchased. The dotplot shows that this data has a roughly bell-shaped distribution. During the twenty one days when the book store owner collected data, at least one book by the author was purchased each day. All of these Correct! Correct! 1 / 1 pts Question 7 A company collected data of the on-hold time for a sample of users calling the customer service. The distribution is displayed in the histogram below.

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 7/22 The distribution shows that the data was highly spread out with some callers waiting on hold as many as 15 minutes. The distribution is symmetrical. The number of callers who waited on hold for less than three minutes was the same as the number of callers who waited on hold for more than three minutes. The distribution is right-skewed and most callers waited on hold less than three minutes. Correct! Correct! The distribution is left-skewed and most callers waited on hold at least three minutes. 1 / 1 pts Question 8 A researcher is interested in finding out the body image perception of college students. She conducted a survey on a sample of 1200 college students on the West Coast . Use the information given in the table to construct a pie chart.

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 8/22 Correct! Correct!

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 9/22 Your answer is correct. 1 / 1 pts Question 9 The side-by-side bar chart displays a company's revenue for two different years divided into four quarters. Which of the following statements is true? (Select all that apply) The revenue difference between the two years was largest in the third quarter Correct! Correct! The revenue for the fourth quarter of Year 2 was $55 million The revenue for the second quarter was the least for both years Correct! Correct! The total revenue decreased from Year 1 to Year 2

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 10/22 Original Score: 0 / 1 pts Regraded Score: 1 / 1 pts Question 10  This question has been regraded. A large state university conducted a survey among their students and received 400 responses. The survey asked the students to provide the following information: "Age" "Year in School (Freshman, Sophomore, Senior)" "Gender" "Major" The university wants to look at students' choice of major between different gender. Which type of graph would be the best way to visualize the data? Histogram Scatterplot Side-by-side bar chart Correct! Correct! Side-by-side boxplot 1 / 1 pts Question 11 The table below presents the relative frequency of exam grades of 60 students divided into intervals of 10 in a statistics class. Score [40, 50) [50, 60) [60, 70) [70, 80) [80, 90) [90, 100] Relative frequency 0.07 0.13 0.27 0.33 0.13 0.07 Which of the following is correct about the distribution of exam scores? (round your answer to the nearest integer)

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 11/22 33 students scored more than 70 on the exam. The lowest exam score among the students is 40. 20 students scored less than 60 on the exam. A student with a score that is exactly 80 will be placed in the bin [80,90) on the histogram. Correct! Correct! 1 / 1 pts Question 12 The reading levels of 41 adults were measured by a certain test. The results were presented in the frequency table below. Which of the following measures can be determined from the table given? (Select all that apply) Mean Mode Median Correct! Correct! Standard deviation Interquartile range Correct! Correct! Range

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 12/22 Your answer is correct. 1 / 1 pts Question 13 The following dot plot shows the values of six data points. The green and red bars represent the current locations of the mean and median. Suppose we now add another point to the data set, which of the following is correct about the changes of mean and median? The median will move to the right if a 7th point was added to the right side of the median. The mean will always be larger than the median, regardless of where you put the 7th point. The mean does not change, regardless of where you put the 7th point. The median does not change, regardless of where you put the 7th point. Correct! Correct! Your answer is correct.

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 13/22 1 / 1 pts Question 14 The boxplot below shows data on income collected from 1000 individuals in a certain region. Which of the following statements about the distribution can be concluded from the plot? (Select all that apply) No potential outlier is identified from the boxplot. Correct! Correct! There are more individuals with income higher than $25,000 than those with income lower than $18,000. Approximately 750 individuals have income less than $25,000. Correct! Correct! The range of the data is $20,000. Correct! Correct! The higher whisker extends to $33,000 which is equal to Q3 + 1.5 IQR. Your answer is correct. 1 / 1 pts Question 15

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 14/22 The table shows the length (in miles) of major rivers in the U.S. Find the mean and standard deviation (round to the nearest integer as needed) and select the correct statement below. The mean length of the major rivers in the world is 1511 miles with a standard deviation of 355 miles. The mean length of the major rivers in the U.S. is 1551 miles with a standard deviation of 328 miles. The mean length of the major rivers in the U.S. is 1511 miles with a standard deviation of 355 miles. Correct! Correct! The mean length of the major rivers in the world is 1551 miles with a standard deviation of 328 miles. 1 / 1 pts Question 16 If the Ohio river (length 979 miles) were added to the major river data set in the previous question,

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 15/22 Answer 1: Answer 2: then the mean will decrease , and the standard deviation will increase . decrease Correct! Correct! increase Correct! Correct! 1 / 1 pts Question 17 Suppose a certain kind of animal on average lives 20 years with a standard deviation of 2.5 years. Assume the distribution is unimodal and symmetric, what percentage of the animal lives longer than 17.5 years ? (Convert your answer to a decimal number, e.g., if the percentage is 1%, you should enter 0.01) 0.84 Correct! Correct! orrect Answers orrect Answers 0.84 (with margin: 0.01) 1 / 1 pts Question 18 Suppose the birth length of newborn babies is has a distribution with a mean of 52.4 centimeters and a standard deviation of 2.5 cm. Assume that the distribution is unimodal and symmetric. We expect to find about 95% of newborn babies with a birth length between 47.4 cm and 57.4 cm. (Round your answers to the nearest tenth as needed)

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 16/22 Answer 1: Answer 2: 47.4 Correct! Correct! 57.4 Correct! Correct! 1 / 1 pts Question 19 Suppose the heights of a group of students have a unimodal and symmetric distribution. The mean is 65 inches and the standard deviation is 3 inches. What does a z-score of -1.2 mean for a student's height? The height of the student is 1.2 inches below the mean The height of the student is -1.2 times that of the mean The height of the student is 61.4 inches Correct! Correct! The height of the student is 68.6 inches 1 / 1 pts Question 20 Suppose the distribution of 3-year-old boys’ heights has a mean of 38 inches and a standard deviation of 2 inches. And the distribution of 10- year-old girls’ heights has a mean of 54.5 inches and a standard deviation of 2.5 inches. A family has two children, Jack and Jill: Jack is a 3-year-old boy at 42 inches tall, while Jill is a 10-year-old girl at 63 inches tall. Assume that both distributions are unimodal and symmetric. Which child has a more unusual height for his or her age and gender?

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 17/22 Jack Jill Correct! Correct! 1 / 1 pts Question 21 If the correlation coefficient between two numerical variables is close to 0, which of the following statements could be true about the scatterplot of the data? (Select all that apply) All the points would lie along a perfectly straight line, with no deviation at all. The scatterplot could be a random cloud of points with no discernible trend. Correct! Correct! The scatterplot could show a strong nonlinear relationship. Correct! Correct! Your answer is correct. 0.67 / 1 pts Question 22 Which of the following is TRUE about the correlation coefficient? (Select all that apply) The correlation coefficient between X and Y and the correlation coefficient between -X and 2Y have the same magnitude but different signs. Correct! Correct!

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 18/22 The correlation coefficient is always between 0 and 1 (including 0 and 1). A correlation coefficient of 1 between X and Y implies that the increase of X causes the increase of Y. You Answered You Answered A pattern that is overall linear but with inconsistent outliers can have a low correlation coefficient. Correct! Correct! The correlation coefficient only makes sense for linear associations. Correct! Correct! 5 / 5 pts Question 23 Data were collected for a random sample of 100 cars and recorded the miles per gallon (mpg) in the city and on the highway. The data were summarized below. City (mpg) Highway (mpg) Mean 29 34 Std Dev 9.7 8.1 r 0.968 Find the least-squares linear regression line that predicts highway mpg from city mpg. Fill the values into the equations and calculate the slope, intercept, and coefficient of determination. ( Round your answers to the nearest hundredth . The format must follow #.##, e.g., 0.01) (i) Calculate the slope (round the final answer to the nearest hundredth, the format must follow #.##, e.g., 0.01) b = 0.968 *( 8.1 / 9.7 ) = 0.81 (ii) Calculate the intercept (use the rounded value of slope b in your calculation and round the final answer to the nearest hundredth, the format must follow #.##, e.g., 0.01)

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 19/22 Answer 1: Answer 2: Answer 3: Answer 4: Answer 5: Answer 6: Answer 7: Answer 8: a = 34 - b* 29 = 10.51 (iii) What is the coefficient of determination of the fitted model? (round the final answer to the nearest hundredth, the format must follow #.##, e.g., 0.01) = 0.94 0.968 Correct! Correct! 8.1 Correct! Correct! 9.7 Correct! Correct! 0.81 Correct! Correct! 34 Correct! Correct! 29 Correct! Correct! 10.51 Correct! Correct! 10.56 orrect Answer orrect Answer 0.94 Correct! Correct! 0.937 orrect Answer orrect Answer

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 20/22 1 / 1 pts Question 24 Suppose that midterm scores and final exam scores in a statistics class are linearly related. The fitted least-squares linear regression model is shown below: Find the most reasonable interpretation of the slope and intercept of the linear model. Slope: For 1 point increase in the midterm score, the final exam score is expected to increase on average by 0.75 point. Intercept : When the midterm score is 0, we expect the final exam score to be 23. Correct! Correct! Slope: For 1 point increase in the final exam score, the midterm score is expected to increase on average by 0.75 point. Intercept : When the final exam score is 0, we expect the midterm score to be 23. Slope: For 1 point increase in the midterm score, the final exam score is expected to decrease on average by 0.75 point. Intercept : When the midterm score is 0, we expect the final exam score to be 0.75. Slope: For 1 point increase in the final exam score, the midterm score is expected to decrease on average by 0.75 point. Intercept : When the midterm score is 0, we expect the final exam score to be 23.

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 21/22 Your answer is correct. 1 / 1 pts Question 25 Answer 1: Suppose that midterm scores and final exam scores in a statistics class are linearly related. The fitted least-squares linear regression model is shown below: A student received a 60 on the midterm in the class, the predicted final exam score for this student is 68 . (Round to the nearest integer) 68 Correct! Correct! 1 / 1 pts Question 26 What effects might an outlier have on a regression model? An outlier may affect only the intercept of a regression equation An outlier may affect only the coefficient of determination An outlier could either increase or decrease the slope, depending on its location Correct! Correct!

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

2/20/22, 12:01 PM Exam 1: 22W-STATS-10-LEC-4 Introduction to Statistical Reasoning https://bruinlearn.ucla.edu/courses/79251/quizzes/778654 22/22 An outlier always increases the slope Quiz Score: 29.67 out of 30

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

stats 10 midterm 1

Related Documents