A study of identity theft looked at how well consumers protect themselves from this increasingly prevalent crime. The behaviors of 63 college students were compared with the behaviors of 59nonstudents. One of the questions was "When asked to create a password, I have used either my mother's maiden name, or my pet's name, or my birth date, or the last four digits of my social security number, or a series of consecutive numbers." For the students, 24 agreed with this statement while 28 of the nonstudents agreed.

(a) Display the data in a two-way table.

Perform the chi-square test. (Round your χ² to three decimal places and round your P-value to four decimal places.)

Summarize the results.

We cannot conclude at the 5% level that students and nonstudents differ in the response to this question.We can conclude at the 5% level that students and nonstudents differ in the response to this question.     

(b) Reanalyze the data using the methods for comparing two proportions that we studied in the previous chapter. Compare the results and verify that the chi-square statistic is the square of the z statistic. (Test students who agreed minus nonstudents who agreed. Round your z to two decimal places and round your P-value to four decimal places.)

(c) The students in this study were junior and senior college students from two sections of a course in Internet marketing at a large northeastern university. The nonstudents were a group of individuals who were recruited to attend commercial focus groups on the West Coast conducted by a lifestyle marketing organization. Discuss how the method of selecting the subjects in this study relates to the conclusions that can be drawn from it.

Determine the 80​% confidence interval estimate for the population mean of a normal distribution given

n=100​, σ=101​, and x (with line over it)=1,200.

a. The 80% confidence interval for the population mean is from _____ to _______.

!!!!!!!!PLEASE SHOW ME HOW TO SOLVE THIS ON EXCEL OR A TI-84 CALCULATOR!!!!!

Simple regression was employed to establish the effects of childhood exposure to lead. The effective sample size was about 122 subjects. The independent variable was the level of dentin lead (parts per million). Below are regressions using various dependent variables.

(a) Calculate the t statistic for each slope. From the p-values, which slopes differ from zero at α = .01? (Round your answers to 2 decimal places. Negative values should be indicated by a minus sign.)

(b) It would be inappropriate to assume cause and effect without a better understanding of how the study was conducted.

• Yes

• No

Below are percentages for annual sales growth and net sales attributed to loyalty card usage at 74 Noodles & Company restaurants.

(b) Find the correlation coefficient. (Round your answer to 3 decimal places. A negative value should be indicated by a minus sign.)
  
r           

(c-1) To test the correlation coefficient for significance at α = 0.1, fill in the following. (Use the rounded value of the correlation coefficient from part b in all calculations. For final answers, round t_calc to 3 decimal places and the p-value to 4 decimal places. Negative values should be indicated by a minus sign.)

(c-2) There is no significant correlation.
  

• False

• True

(d) Does it appear that increased loyalty card usage is associated with decreased sales growth?
  

• Yes

• No

Next

Suppose that an accounting firm does a study to determine the time needed to complete one person's tax forms. It randomly surveys 150 people. The sample mean is 23.1 hours. There is a known population standard deviation of 6.4 hours. The population distribution is assumed to be normal.

NOTE: If you are using a Student's t-distribution, you may assume that the underlying population is normally distributed. (In general, you must first prove that assumption, though.)

• Part (a)

  Find the following. (Enter exact numbers as integers, fractions, or decimals.)(i)    

  x =

  
  
  (ii)    

  σ =

  
  
  (iii)    

  n =

• Part (b)

  In words, define the random variables X and X

  X is the number of tax forms that an accounting firm completes, and X is the mean number of tax forms that an accounting firm completes.X is the number of tax forms that an accounting firm completes, and X is the mean number of tax forms that an accounting firm completes.    X is the time needed to complete one person's tax forms, and X is the mean time needed to complete tax forms from a sample of 150 customers.X is the time needed to complete one person's tax forms, and X is the mean time needed to complete tax forms from a sample of 150 customers.

• Part (c)

  Which distribution should you use for this problem? (Round your answers to two decimal places.)

  X ~

    ? Exp N B H U   ,  
  
  Explain your choice.

  The standard normal distribution should be used because the mean is given.The Student's t-distribution should be used because the sample mean is smaller than 30.    The standard normal distribution should be used because the population standard deviation is known.The Student's t-distribution should be used because the sample standard deviation is given.

• Part (d)

  Construct a 90% confidence interval for the population mean time to complete the tax forms.(i) State the confidence interval. (Round your answers to two decimal places.)   ,  
  
  (ii) Sketch the graph. (Round your answers to two decimal places.) (iii) Calculate the error bound. (Round your answer to two decimal places.)

• Part (e)

  If the firm wished to increase its level of confidence and keep the error bound the same by taking another survey, what change should it make?

  It should increase the number of people surveyed.It should decrease the number of people surveyed.    

• Part (f)

  If the firm did another survey, kept the error bound the same, and only surveyed 49 people, what would happen to the level of confidence? Why?

  The level of confidence would be larger because we have collected a smaller sample, obtaining less accurate information.The level of confidence would be smaller because we have collected a smaller sample, obtaining less accurate information.    There would be no change.

• Part (g)

  Suppose that the firm decided that it needed to be at least 96% confident of the population mean length of time to within one hour. How would the number of people the firm surveys change? Why?

  The number of people surveyed would decrease because more accurate information requires a smaller sample.The number of people surveyed would increase because more accurate information requires a larger sample.    There would be no change.

Annual expenditures for prescription drugs was $838 per person in the Northeast of the country. A sample of 60 individuals in the Midwest showed a per person annual expenditure for prescription drugs of $745. Suppose the population standard deviation is $300. Follow the steps below to develop a hypothesis test to determine whether the sample data support the conclusion that the population annual expenditure for prescription drugs per person is lower in the Midwest than in the Northeast.

1. Formulate the null and alternative hypotheses.  State whether this is a one-tailed test (and if so, upper or lower tail) or a two-tailed test.
2. Suppose the significance level is . Explain what this means.
3. Calculate the test statistic. (Hint: Is  known or unknown?)
4. Calculate the p-value and make a decision to either reject  or to fail to reject .
5. Calculate the critical value(s). Use the test statistic then to make a decision to either reject  or to fail to reject .
6. State what your decision means in the context of the problem (prescription expenditure in the Midwest vs. the Northeast).

10. In a recent study on world​ happiness, participants were asked to evaluate their current lives on a scale from 0 to​ 10, where 0 represents the worst possible life and 10 represents the best possible life. The responses were normally​distributed, with a mean of 5.8 and a standard deviation of 2.3.

A. The probability that a randomly selected study​ participant's response was less than 4 is __.

B.The probability that a randomly selected study​ participant's response was between 4 and 6 is __.

C. The probability that a randomly selected study​ participant's response was more than 8 is __.

​D.  Identify any unusual events. Explain your reasoning. Choose the correct answer below.

A.The event in part left parenthesis a right parenthesis(a) is unusual because its probability is less than 0.05.

B.The events in parts left parenthesis a right parenthesis and left parenthesis c right parenthesis(a) and (c) are unusual because their probabilities are less than 0.05.

C. There are no unusual events because all the probabilities are greaterThere are no unusual events because all the probabilities are greater than 0.05.

D. The events in parts left parenthesis a right parenthesis comma left parenthesis b right parenthesis comma and left parenthesis c right parenthesis are unusual because all of their probabilities areThe events in parts (a), (b), and (c) are unusual because all of their probabilities are less than 0.05.

11. Use the standard normal table to find the​ z-score that corresponds to the cumulative area 0.6312. If the area is not in the​ table, use the entry closest to the area. If the area is halfway between two​ entries, use the​ z-score halfway between the corresponding​ z-scores.

z=__.

12. Use the standard normal table to find the​ z-score that corresponds to the given percentile. If the area is not in the​ table, use the entry closest to the area. If the area is halfway between two​ entries, use the​ z-score halfway between the corresponding​ z-scores. If​ convenient, use technology to find the​ z-score.

P15

The​ z-score that corresponds to P15 is __.

Why do independent group designs tend to be less powerful than dependent group designs? What circumstances give rise to dependent group designs not being more powerful than independent group designs?

Allen's hummingbird (Selasphorus sasin) has been studied by zoologist Bill Alther.† Suppose a small group of 12 Allen's hummingbirds has been under study in Arizona. The average weight for these birds is x = 3.15 grams. Based on previous studies, we can assume that the weights of Allen's hummingbirds have a normal distribution, with σ = 0.20 gram.

(a)

Find an 80% confidence interval for the average weights of Allen's hummingbirds in the study region. What is the margin of error? (Round your answers to two decimal places.)

lower limitupper limitmargin of error

(b)

What conditions are necessary for your calculations? (Select all that apply.)

σ is knownσ is unknownn is largenormal distribution of weightsuniform distribution of weights

(c)

Interpret your results in the context of this problem.

There is a 20% chance that the interval is one of the intervals containing the true average weight of Allen's hummingbirds in this region.The probability that this interval contains the true average weight of Allen's hummingbirds is 0.20.    There is an 80% chance that the interval is one of the intervals containing the true average weight of Allen's hummingbirds in this region.The probability that this interval contains the true average weight of Allen's hummingbirds is 0.80.The probability to the true average weight of Allen's hummingbirds is equal to the sample mean.

(d)

Find the sample size necessary for an 80% confidence level with a maximal margin of error E = 0.09 for the mean weights of the hummingbirds. (Round up to the nearest whole number.)

hummingbirds

Suppose you roll, two 6-sided dice (refer back to the sample space in the sample space notes). Write any probability as a decimal to three place values and the odds using a colon. Determine the following:

a. the probability that you roll a sum of seven (7) is .

b. The odds for rolling a sum of four (4) is .

c. The odds against the numbers on both dice being the same is .

Rounded to 4 decimal, what is the standard deviation of a binomila distribution that uses 216 trials with a success probability of 0.17?

Rounded to 4 decimal, what is the standard deviation of a binomila distribution that uses 23 trials with a success probability of 0.85?

Rounded to 4 decimal, what is the standard deviation of a binomila distribution that uses 31 trials with a success probability of 0.19?

Suppose that 1 out of 4 eggs contain the Salmonella virus, and eggs are independent of each other with regard to having Salmonella. If Sue uses 3 eggs to bake a cake, the distribution describing the probability of getting eggs with the virus is

Which of the following is a characteristic of the binomial distribution?

A coin is weighted so that it turns up heads 60% of the time. If the coin is flipped 10 times, and the flips are independent of each other, the distribution is

Which of the following is not a characteristic of a binomial distrIbution?

As the number of trials gets large, a binomial distribution starts to resemble a

In order for n to be large enough for the normal distribution to be able to approximate the binomial, n must be

a. np > 10

b. np > 10 and n(1-p) > 10

c. n > 100

d. n > 100 and p > 0.1

Two cards are drawn at random from an ordinary deck of 52 playing cards. If the two cards display the same suit, you win $2. If they are the same color only, you win $1. Otherwise, you lose 50 cent. Calculate

(a) the expected value of the amount you win;

(b) the variance of the amount you win;

Refer to the accompanying technology display. The probabilities in the display were obtained using the values of n equals 5 and p equals 0.759. In a clinical test of a​ drug, 75.9​% of the subjects treated with 10 mg of the drug experienced headaches. In each​ case, assume that 5 subjects are randomly selected and treated with 10 mg of the drug. Find the probability that more than one subject experiences headaches. Is it reasonable to expect that more than one subject will experience​ headaches?

0 0.0008

1. 0.0128

2. 0.0806

3. 0.2540

4. 0.3999

5. 0.2519

The probability that more than one subject experiences headaches is ________ ?

The probability that more than one subject experiences headaches is Is it reasonable to expect that more than one subject will experience headaches?

Yes: because the event that the number of subjects that experience headaches is less than or equal to one is not unlikely. No, because the event that the number of subjects that experience headaches is less than or equal to one is not unlikely. Yes: because the event that the number of subjects that experience headaches is less than or equal to one is unlikely. No, because the event that the number of subjects that experience headaches is less than or equal to one is unlikely.

Each year a market research company surveys new car owners 90 days after they purchase their cars. This data is used to rate auto brands (such as Toyota and Ford) on quality and customer satisfaction. Suppose the following were the quality rating and satisfaction scores for all 33 brands sold in the United States.

A)

Compute the value of the correlation coefficient. (Round your answer to three decimal places.)

r =  

Answer A!...