Provide an appropriate response.

1.The table below shows the number of homicides in the U.S. in each of the years 1989-1993

Classify the study as either descriptive or inferential.

Descriptive Inferential

2.An employee at the local ice cream parlor asks three customers if they like chocolate ice cream.

Identify the sample and population.

Sample: the customers who like chocolate ice cream; population: all customers

Sample: the 3 selected customers; population: all customers

Sample: all customers; population: the 3 selected customers

Sample: the 3 selected customers; population: the customers who like chocolate ice cream

3.The number of cars passing a busy intersection between 4:30 P.M. and 6:30 P.M. on a Monday is

2,200.

Discrete Continuous

4.A large record company reported the following sales figures for various music media last year.

What kind of data is provided by the information in the second column?

Qualitative Quantitative

5.Lori asked 24 students how many hours they had spent doing homework during the

previous week. The results are shown below.

10 11 10 8 10 10 14 12 10 9 12 11

11 12 10 11 12 10 11 12 11 12 12 8

Construct a frequency distribution. Use 4 classes, a class width of 2 hours, and a lower limit

of 8 for the first class.

HOURS

Frequency

6.The data in the following table reflect the amount of time 40 students in a section of Statistics 101

spend on homework each day. Determine the value that should be entered in the relative frequency

column for the class 45-59.

Homework time

(minutes)

Number of

students

Relative

frequency

0-14

2

15-29

4

30-44

10

45-59

16

60-74

6

75-89

2

7.The midterm test scores for the seventh-period typing class are listed below. Construct a stem-and-leaf diagram for the given data.

85 77 93 91 74 65 68 97

88 59 74 83 85 72 63 79

5

6

7

8

9

8.The partially filled contingency table gives the frequencies of the data on age (in years) and sex

from the residents of a retirement home.

Age (yrs)

60-69

70-79

Over 79

Total

Male

11

10

5

Female

9

1

4

Total

What percentage of residents are males in the age group 60-69 ?

9.The ages of a group of patients being treated at one hospital for osteoporosis are summarized in the

frequency histogram below.

Right skewed

Left skewed

Reverse J-shaped

Bell-shaped

10.The students in Hugh Logan's math class took the Scholastic Aptitude Test. Their math scores are

shown below. Find the mean score.

580 533 348 340 499

342 350 575 470 482

476

461.1

451.9

443

11.The normal annual precipitation (in inches) is given below for 21 different U.S. cities. Find the first

quartile, Q1

39.1 16.2 25.4 18.3 27.1 27.8 30.6

15.6 42.6 18.3 13.9 19.2 32.3 10.6

14.1 33.6 12.6 35.0 22.3 11.9 51.7

14.85 in.

14.1 in.

14.475 in.

15.6 in.

12.Is it any differences between the interquartile range and the range. Explain answer.

13.A variable x has a mean, , of 19.4 and a standard deviation, of 3.6. Determine the z-score

corresponding to an observed value for x of 25.8. Round your final answer to two decimal places.

1.78

12.56

-1.78

1.14

14.If you flip a coin three times, the possible outcomes are HHH HHT HTH HTT THH THT TTH TTT. What is the probability of getting at least two tails?

3/8

1/2

5/8

1/8

15.In a competition, two people will be selected from four finalists to receive the first and second

prizes. The prize winners will be selected by drawing names from a hat. The names of the four

finalists are Jim, George, Helen, and Maggie. The possible outcomes can be represented as follows.

JG JH JM GJ GH GM

HJ HG HM MJ MG MH

Here, for example, JG represents the outcome that Jim receives the first prize and George receives

the second prize. List the outcomes that comprise the following event.

A = event that Helen gets a prize

JH, GH, HJ, JG, HG, HM, MH

HJ, HG, HM

JH, GH, HJ, HG, HM

JH, GH, HJ, HG, HM, MH

16.The age distribution of students at a community college is given below.

A student from the community college is selected at random. The events A and B are defined as

follows.

A = event the student is between 21 and 40 inclusive

B = event the student is over 25

Describe the event (A or B) in words.

The event the student is between 24 and 25 inclusive

The event the student is 21 or over

The event the student is between 21 and 25 inclusive

The event the student is between 25 and 40 inclusive

17.Suppose a coin is tossed four times. Let X denote the total number of tails obtained in the four

tosses. Use random-variable notation to represent the event that the total number of tails is three.

{X 3}

HTTT, THTT, TTHT, TTTH

{X = 3}

P{X = 3}

18.Suppose that W is a random variable. Given that P (W 3) = 0.625, find P(W > 3)

0.625

0.375

0

3

19.Evaluate the expression.

9!

40,320

362,889

362,871

362,880

20.The percentage of all possible observations of the variable that lie between 6 and 12 equals the area

under its density curve between and , expressed as a percentage.

A) 6, 12B) 0.06, 0.12C) 3, 6D) 7, 13

21.Fill in the blanks by standardizing the normally distributed variable.

Dave drives to work each morning at about the same time. His commute time is normally

distributed with a mean of 54 minutes and a standard deviation of 7 minutes. The percentage of

time that his commute time lies between 40 and 75 minutes is equal to the area under the standard normal curve between ___ and ___.

A) -2.5, 2.5B) -1.5, 3.5C) 0, 1D) -2, 3

22.Frequency data were reported for the ages of full-time employees at a company. The age

distribution is given in the table. Obtain a relative-frequency histogram of these data and

determine whether the ages are approximately normally distributed.

A) Yes. The distribution is bell-shaped.

B) No. The distribution is uniform.

C) No. The distribution is left-skewed.

D) No. The distribution is right-skewed.

23.Use a table of areas for the standard normal curve to find the required z-score.

Find the z-score for which the area under the standard normal curve to its left is 0.96

A) 1.75

B) 1.82

C) -1.38

D) 1.03

24.Does the presence of an outlier in your data set necessarily mean that you cannot use the

normal model to interpret the data?

25.Based on a sample of 30 randomly selected years, a 90% confidence interval for the mean annual

precipitation in one city is from 40.3 inches to 43.7 inches. Find the margin of error.

A) 3.4 inches

B) There is not enough information to find the margin of error.

C) 1.7 inches

D) 0.51

26.A college statistics professor has office hours from 9:00 A.M. to 10:30 A.M. daily. A sample of

waiting times to see the professor (in minutes) is 10, 12, 20, 15, 17, 10, 30, 28, 35, 28, 19, 27, 25, 22, 33,

37, 14, 21, 20, 23. Assuming = 7.84, find the 95.44% confidence interval for the population mean.

A) -3.5 to 3.5 minutes

B) 19.5 to 35.1 minutes

C) 18.8 to 25.8 minutes

D) -7.7 to 7.8 minutes

27.In stating a confidence-interval estimate of a population mean, the level of confidence increases as

the size of the interval .

A) decreases

B) increases

28.A confidence interval for a population mean, , has length 104.6. Find the margin of error. 23)

A) 209.2

B) 52.3

C) 104.6

D) 10,941.16

29.A hypothesis test is to be performed. Determine the null and alternative hypotheses. In the past, the mean running time for a certain type of flashlight battery has been 8.0 hours. The

manufacturer has introduced a change in the production method and wants to perform a

hypothesis test to determine whether the mean running time has changed as a result.

A) H₀ : 8.0 hours

Ha : = 8.0 hours

B) H₀ : = 8.0 hours

Ha : > 8.0 hours

C) H₀ : = 8.0 hours

Ha : 8.0 hours

D) H₀ : 8.0 hours

Ha : = 8.0 hours

30.The recommended dietary allowance (RDA) of vitamin C for women is 75 milligrams per day. A

hypothesis test is to be performed to decide whether adult women are, on average, getting less than

the RDA of 75 milligrams per day.

A) Two-tailedB) Left-tailedC) Right-tailed

31.For the given hypothesis test, explain the meaning of a Type I error, a Type II error, or a correct decision as specified.

In the past, the mean running time for a certain type of flashlight battery has been 9.7 hours. The

manufacturer has introduced a change in the production method and wants to perform a

hypothesis test to determine whether the mean running time has increased as a result. The

hypotheses are:

H0 : = 9.7 hours

Ha : > 9.7 hours

where is the mean running time of the new batteries . Explain the meaning of a Type I error.

A) A Type I error would occur if, in fact, > 9.7 hours, but the results of the sampling lead to the

conclusion that < 9.7 hours.

B) A Type I error would occur if, in fact, = 9.7 hours, but the results of the sampling lead to the

conclusion that > 9.7 hours.

C) A Type I error would occur if, in fact, = 9.7 hours, but the results of the sampling do not lead

to rejection of that fact.

D) A Type I error would occur if, in fact, > 9.7 hours, but the results of the sampling fail to lead

to that conclusion.

32.A graphical display of the decision criterion follows.

Determine the nonrejection region.

A) z 0.01

B) z -2.33 or z 2.33

C) -2.33 z 2.33

D) z = -2.33 or z = 2.33