Concept explainers
The paper “If It’s Hard to Read, It’s Hard to Do” (Psychological Science [2008]: 986–988) described an interesting study of how people perceive the effort required to do certain tasks. Each of 20 students was randomly assigned to one of two groups. One group was given instructions for an exercise routine that were printed in an easy-to-read font (Arial). The other group received the same set of instructions, but printed in a font that is considered difficult to read (Brush).
After reading the instructions, subjects estimated the time (in minutes) they thought it would take to complete the exercise routine. Summary statistics are given below.
The authors of the paper used these data to carry out a two-sample t test, and concluded that at the 0.10 significance level, there was convincing evidence that the
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Chapter 11 Solutions
Introduction To Statistics And Data Analysis
- What is meant by the sample space of an experiment?arrow_forwardWhat is a sample space?arrow_forwardIn a study of high school students at least 16 years of age, researchers obtained the survey results summarized in the table below (based on data from “Texting While Driving and Other Risk Motor Vehicle Behaviors Among U.S. High School Students” by O’Malley, Shults, and Eaton, Pediatrics, 131, No.6). Irregular Seat Belt Use? Yes No RT Texted While Driving 1737 2048 3785 Did not Text While Driving 1945 2775 4720 Column total 3682 4823 8505 State the null and alternative hypotheses. Null hypothesis: H0 Texting when driving is independent of irregular seat belt use. Alternative hypothesis: Texting when driving is dependent of irregular seat belt use. Assuming independence, what are the expected frequencies for each of these variables? E=(row total)(column total) (grand total) What is the value of the X2 statistic? X2=E(0-E)2…arrow_forward
- A market researcher for an automobile company suspects differences in preferred color between male and female buyers. Advertisements targeted to different groups should take such differences into account, if they exist. The researcher examines the most recent sales information of a particular car that comes in three colors. (You may find it useful to reference the appropriate table: chi- square table or F table) Sex of Automobile Buyer. Male Color Female Silver 477 298 Black 536 308 Red 482 348 a. Choose the competing hypotheses to determine whether color preference depends on the automobile buyer's sex. O Họ Color preference is independent of the automobile buyer's sex.: HA Color preference is dependent on the automobile buyer's sex. O Ho Color preference is dependent on the automobile buyer's sex; HA: Color preference is independent of the automobile buyer's sex. b-1. Calculate the value of the test statistic. (Round the intermediate calculations to at least 4 decimal places and…arrow_forwardDo d, e and f part of the question thank youarrow_forwardA study was conducted to determine whether big-city and small-town dwellers differed in their helpfulness to strangers. In the study, the investigators rang the doorbells of strangers living in Toronto or small towns in the vicinity. They explained they had misplaced the address of a friend living in the neighborhood and asked to use the phone. The following data show the number of individuals who admitted or did not admit the strangers (the investigators) into their homes: Admitted strangersinto their home Did not admit strangersinto their home Big-city dweller 60 90 Small-town dweller 70 30 Conduct a chi-squared test to examine whether big-city dwellers differ in their helpfulness to strangers. Which of the following is/are true about the result of the test? A. The obtained chi-squared test statistic is 21.6346. B. The obtained pp-value is approximately 0. C. The obtained chi-squared test statistic is 8.450. D. The obtained…arrow_forward
- A report described teens' attitudes about traditional media, such as TV, movies, and newspapers. In a representative sample of American teenage girls, 42% said newspapers were boring. In a representative sample of American teenage boys, 45% said newspapers were boring. Sample sizes were not given in the report. A button hyperlink to the SALT program that reads: Use SALT. (a) Suppose that the percentages reported had been based on a sample of 50 girls and 40 boys. Is there convincing evidence that the proportion of those who think that newspapers are boring is different for teenage girls and boys? Carry out a hypothesis test using ? = 0.05. (Use pgirls − pboys.) Find the test statistic. (Round your answer to two decimal places.) z = Find the P-value. (Round your answer to four decimal places.) P-value = State your conclusion. Reject H0. We do not have convincing evidence that the proportion of girls who say that newspapers are boring is different from the proportion of boys who…arrow_forwardA Doctor is interested in the proportion of Lyon county residents who were infected with covid-19 virus. There were 425 covid-19 cases reported among 25474 residents in Lyon county. a. What is a statistics in this experiment? b. What variables should pollster collect in this experiment?arrow_forwardA researcher is interested in whether completing a six-week speed-reading course designed for sighted readers affects reading speed among blind Braille readers. She has blind adults complete a reading speed test before and after a six-week speed-reading course. The researcher randomly selects a sample of 50 blind Braille readers who, at the beginning of the study, scored an average of 261 words per minute on the reading speed test. After the speed-reading course, the blind Braille readers scored an average of 7 words per minute higher. The standard deviation of the difference scores was 21. Since the sample size is larger than 30, the researcher can assume that the sampling distribution of MD is normal. She uses a repeated-measures t test to test that the mean difference is zero, and she describes the results as follows: After the speed-reading course, the Braille reading speed among blind Braille readers is significantly different than before taking the course, t(49) = 2.36, p =…arrow_forward
- A teacher is interested in the effect of a study session on quiz performance. Two different classes receive a pretest and a posttest. Thus, the teacher records the following four set of scores: Class 1 pretest = (5, 8, 9, 10, 12, 12, 14) Class 1 posttest = (18, 18, 20, 20, 20, 20, 24) Class 2 pretest = (2, 4, 8, 12, 12, 12, 20) Class 2 posttest = (10, 12, 20, 21, 21, 28, 28) For each of for sets of scores above, calculate the sample mean and standard deviation. In which class is the effect of the study session most obvious in the pattern of data?arrow_forwardDo people feel hungrier after sampling a healthy food? The authors of a consumer research paper carried out a study to answer this question. They randomly assigned volunteers into one of three groups. The people in the first group were asked to taste a snack that was described as a new health bar containing high levels of protein, vitamins, and fiber. The people in the second group were asked to taste the same snack but were told it was a tasty chocolate bar with a raspberry center. After tasting the snack, participants were asked to rate their hunger level on a scale from 1 (not at all hungry) to 7 (very hungry). The people in the third group were asked to rate their hunger but were not given a snack. The data in the table are consistent with summary quantities given in the paper (although the sample sizes in the actual study were larger). Treatment Group Healthy Tasty 5 8 7 Hunger Rating No Snack 3 4 4 4 1 4 2 7 3 6 2 5 6 5 5 4 7 5 2 3 4 6 4 4 Sample Mean 5.6667 3.4444 4.2222 Sample…arrow_forwardDo people feel hungrier after sampling a healthy food? The authors of a consumer research paper carried out a study to answer this question. They randomly assigned volunteers into one of three groups. The people in the first group were asked to taste a snack that was described as a new health bar containing high levels of protein, vitamins, and fiber. The people in the second group were asked to taste the same snack but were told it was a tasty chocolate bar with a raspberry center. After tasting the snack, participants were asked to rate their hunger level on a scale from 1 (not at all hungry) to 7 (very hungry). The people in the third group were asked to rate their hunger but were not given a snack. The data in the table are consistent with summary quantities given in the paper (although the sample sizes in the actual study were larger). TreatmentGroup Hunger Rating SampleMean SampleStandardDeviation Healthy 5 8 7 4 7 3 4 7 6 5.6667 1.7321 Tasty 4 1 5 2 6 2 5 3 4 3.5556…arrow_forward
- Holt Mcdougal Larson Pre-algebra: Student Edition...AlgebraISBN:9780547587776Author:HOLT MCDOUGALPublisher:HOLT MCDOUGALGlencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw HillCollege Algebra (MindTap Course List)AlgebraISBN:9781305652231Author:R. David Gustafson, Jeff HughesPublisher:Cengage Learning