- (3points)Foreachofthefollowingstatisticalsummaries,explainwhetheritisapopulationparameterora sample statistic.
- (a) The average score on the first midterm exam is 79.8% for n = 32 students in a statistics class. The instructor is intersted in describing the performance of the five classes at the university using this one class.
- (b) The average score on the first midterm exam is 79.8% for n = 32 students in a statistics class. The instructor is only interested in describing the performance of this particular class.
- (5 points) In 1998 a headline in USA Today read, "Prayer can lower blood pressure." The story stated that "attending religious services lowers blood pressure more than turning into religious TV or radio." This article was based on an observational study which followed 2391 people aged 65 or over for 6 years. They found that people who attend a religious service once a week and prayed or studied the Bible once a day were 40% less likely to have high blood pressure than those who didn't go to church every week and prayed and studied the Bible less.
- (a) (1 point) What was the sample size for this observational study? (b) (1 point) Describe the observational units in this study.
- (c) (2 points) Identify the explanatory and response variables in this study.
- (d) (1 point) Can you conclude that prayer actually causes lower blood pressure? Why or why not?
- (4 points) Give examples of the following types of variables:

Fall 2018

1 Ch. 2

(a) an ordinal categorical variable.

(c) a continuous quantitative variable.

(b) a categorical variable that is not ordinal.

(d) a quantitative variable that is not continuous.

Name: Ch. 2 WH /50

- (3 points) In In the 2008 General Social Survey, participants were asked, "Would you say that you are very happy, pretty happy, or not too happy?" The results were that 610 people said they were very happy, 1210 people said pretty happy, and 326 people said not too happy. (
*Data source:*http://sda.berkeley.edu). Find the percentage in each of the three response categories. Give your answers as percentages rounded to the nearest hundreth. (e.g. 10.15%) - (4 points) According to the CDC, the age distribution for mothers in the United States who had a first child in 2014 was as follow. Draw a bar graph to represent the data. Clearly label your axes. Does the data appear to have a left skew, right skew or no skew?

Under 20

20-24

25-29

30-34

35 and Over

10.4%

32.1 %

27.7%

21.1 %

9.1 %

6. (4points)Ahypotheticalstudentinthisclasslastsemesterhadthefollowingscoresonfive0,82,88,90,96, which represent scores on five written homework assignments.

- (a) (2 points) Find the mean and median of the scores on the five written homework assignments.
- (b) (1 point) Explain why there is such a large difference between the mean and median values. (Word to the wise, this explains why skipping assignments is a terrible idea!)
- (c) (1 point) Suppose rather than taking a zero on one assignment the student had instead submitted a half-completed assignment and earned a 50. What would the mean be if the first assignment's score was replaced with a 50?

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2 Ch. 2

Name: Ch. 2 WH /507. (10 points) A set of eight systolic blood pressures follows:

110, 123, 132, 150, 127, 118, 102, 122(a) (4 points) Create a five-number summary of the data.

(b) (3 points) Clearly identify whether or not there are any outliers in the dataset. Explain your answer using numbers.

(c) (3 points) Draw a box-plot of the blood pressures.

8. (3 points) Suppose that the distribution of speeds at on a city street is bell-shaped with a median of 45 mph and a standard deviation of 1.9 mph. Use the Empirical Rule to complete each sentence.

(a) About 68% of vehicles at this location travel between and mph. (b) About 95% of vehicles at this location travel between and mph.

(c) About 99.7% of vehicles at this location travel between and mph.

Fall 2018 3

Ch. 2

Name: Ch. 2 WH /509. (5points)Therestingheartrates,inbeatsperminute,ofsixmarathonrunnersisgivenby52,45,60,62,48,48

(a) (1 point) Find the mean for these data.

(b) (3 points) Find the standard deviation for these data. Show all work.

(c) (1 point) What is the variance for these data?

- (6points)Supposethattheamountspentontextbooksinasemesterforcollegestudentshasameanof$350. Suppose you spend $450 on textbooks.
- (a) Suppose the standard deviation is $100. Compute the z-score for your $450 textbook purchase. Is spending $450 unusual in this case? Why or why not?
- (b) Suppose the standard deviation is $25. Compute the z-score for your $450 textbook purchase. Is spending $450 unusual in this case? Why or why not?
- (3 points) Suppose verbal ACT scores for students admitted to a university are bell-shaped with a mean of 21 and a standard deviation of 3.
- (a) What is the ACT score such that only 16 % of students admitted have a higher score?
- (b) What is the ACT score such that only 2.5% of students admitted have a lower score?
- (c) What is the ACT score such that only 0.15% of students admitted have a lower score?

### Recently Asked Questions

- Please refer to the attachment to answer this question. This question was created from Chap004-cases_and_reading.

- Please refer to the attachment to answer this question. This question was created from Chap004-cases_and_reading. Additional comments: "How to solve this? "

- The state office of Australia Post believed that mail throughput at suburban post offices increases with the number of employees. From a random sample of ten