How many days in advance do travelers purchase their airline tickets? Below are data showing the
advance days for a sample of 13 passengers on United Airlines Flight 812 from Chicago to Los Angeles.

11, 7, 11, 4, 15, 14, 71
29, 8, 7, 16, 29, 249

(a) Calculate the mean, median, and mode.
(b) Which is the best measure of central tendency? Why?
(c) Base on your discussion in part (b), which is the best measure of variation? Determine its
value.

Concrete blocks are produced in lots of 2000. Each block has probability 0.85 of meeting a strength specification. The blocks are independent.

NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part.

1-What is the probability that, in a given lot, fewer than 1690 blocks meet the specification?

2-Find the 70th percentile of the number of blocks that meet the specification.

3-In a group of six lots, what is the probability that fewer than 1690 blocks meet the specification in three or more of them?

Sherds of clay vessels were put together to reconstruct rim diameters of the original ceramic vessels at the Wind Mountain archaeological site†. A random sample of ceramic vessels gave the following rim diameters (in centimeters).

(a) Use a calculator with mean and sample standard deviation keys to find the sample mean x and sample standard deviation s. (Round your answers to one decimal place.)

(b) Compute a 98% confidence interval for the population mean μ of rim diameters for such ceramic vessels found at the Wind Mountain archaeological site. (Round your answers to one decimal place.)

In a study of cell phone use and brain hemispheric​ dominance, an Internet survey was​ e-mailed to

2592

subjects randomly selected from an online group involved with ears.

913

surveys were returned. Construct a

99​%

confidence interval for the proportion of returned surveys.

You may need to use the appropriate technology to answer this question.

A production line operation is tested for filling weight accuracy using the following hypotheses.

The sample size is 30 and the population standard deviation is σ = 0.7 Use α = 0.05.

What is the probability of making a type II error when the machine is overfilling by 0.4 ounces? (Round your answer to four decimal places.)

What is the power of the statistical test when the machine is overfilling by 0.4 ounces? (Round your answer to four decimal places.)

(The life in hours of a heating element used in a furnace is known to be approximately normally distributed. A random sample of 15 heating elements is selected and found to have an average life of 598.14 hours and a sample standard deviation of 16.93 hours.

(a) Test the claim that the true average life is greater than 550 hours. Be sure to state Hypotheses clearly, give all summary data, state Test used, show Test Statistics formula and value, and show how to find the P-value. Write an appropriate conclusion using α = 0.05. 7

(b) Test the claim that the true average life is equal to 610 hours. Be sure to state Hypotheses clearly, give all summary data, state Test used, show Test Statistics formula and value, and show how to find the P-value. Write an appropriate conclusion using α = 0.01.

Given that z is a standard normal random variable, compute the probability that it takes on a value between -2 and -1.

A person must score in the upper 2% of the population on an IQ test to qualify for membership in Mensa, the international high-IQ society. If IQ scores are normally distributed with a mean of 100 and a standard deviation of 15, what score must a person have to qualify for Mensa?

Homework – Problem #1

High-Low, Scattergraph, Regression Analysis, and P & L Statement: Eye Care, Inc., provides vision correction surgery for its patients. You are the accountant for Eye Care, and management has asked you to devise a way of accurately estimating company costs for planning and decision-making purposes. You believe that reviewing historical data for costs and number of surgeries is the best starting point. These data are as follows:

Required:

1. Use the four steps of the high-low method to estimate total fixed costs per month, and the variable cost per surgery. State your results in the cost equation form Y = f + vX by filling in the dollar amounts for f and v. Explain.
2. Use the five steps of the scattergraph method to estimate total fixed costs per month, and the variable cost per surgery. State your results in the cost equation form Y = f + vX by filling in the dollar amounts for f and v. Explain.
3. Use the regression output given to develop the cost equation Y = f + vX by filling in the dollar amounts for f and v. Explain.
4. Use the results of the high-low method (a), scattergraph method (b), and regression analysis (c), to estimate costs for 70 surgeries. (You will have three different answers—one for each metho) Which approach do you think is most cost efficient and why? Explain.
5. Assume Eye Care charges $4,000 for each surgery performed. Use the regression analysis cost information (for 70 surgeries) to prepare a P & L statement. Explain the results.

the number of initial public offerings of stock issued in a 10-year period and the total proceeds of these offerings (in million) are shown in the table. Construct and interpret a 95% prediction interval for the proceeds when the number of issues is 576. The equation of the regression line is ý = 32.688x + 17,464.523.

Issues, x 412 458 700 483 483 392 52 75 176 170

proceeds 17,976   29,418 43,736 30,522 36,578 35,848 20,092, 11,034 31,749 28,865

construct and interpret a 95% prediction interval for the proceeds when the number of issues is 576.

select the correct choice below and fill in the answer boxes to complete your choice.
(round to the nearest million dollars as needed. type your answer in standard form where "3.12 million" means 3,120,000)

A. we can be 95% confident that when there are 576 issues, the proceeds will be between $____ and $_____

or
B. There is a 95% chance that the predicted proceeds given 576 issues is between $___ and $____

Do female college students spend more time than male college students watching TV? This was one of the questions investigated by the authors of an article. Each student in a random sample of 46 male students at a university in England and each student in a random sample of 38 female students from the same university kept a diary of how he or she spent time over a three-week period.

For the sample of males, the mean time spent watching TV per day was 68.8 minutes and the standard deviation was 67.5 minutes. For the sample of females, the mean time spent watching TV per day was 93.8 minutes and the standard deviation was 89.1 minutes. Is there convincing evidence that the mean time female students at this university spend watching TV is greater than the mean time for male students? Test the appropriate hypotheses using

α = 0.05.

(Use a statistical computer package to calculate the P-value. Use μ_males − μ_females. Round your test statistic to two decimal places, your df down to the nearest whole number, and your P-value to three decimal places.)

State your conclusion.

a.Reject H₀. We do not have convincing evidence that the mean time female students at this university spend watching TV is greater than the mean time for male students.

b.Fail to reject H₀. We have convincing evidence that the mean time female students at this university spend watching TV is greater than the mean time for male students.     

c.Reject H₀. We have convincing evidence that the mean time female students at this university spend watching TV is greater than the mean time for male students.

d.Fail to reject H₀. We do not have convincing evidence that the mean time female students at this university spend watching TV is greater than the mean time for male students.

compare the similarities and differences in the sampling, methodologies, and findings in two studies of your choice

one being an experiment and a quasi-experiment

1. A recent study on the effect of raw garlic on plasma lipid concentration in adults with moderate hypercholesterolemia was conducted using 49 randomly selected subjects treated with raw garlic and 48 randomly selected subjects with a placebo.

The 49 subjects treated with raw garlic had LDL cholesterol measurements with a mean of 151 and a standard deviation of 15, while 48 subjects given placebos had LDL cholesterol measurements with a mean of 149 and a standard deviation of 14.

Use a 0.05 significance level to test the claim that there is no difference between the mean LDL cholesterol levels of subjects treated with raw garlic and subjects given placebos.

1. Check requirements first.

2. If requirements are met, list each of the 8 steps in a hypothesis test to test the claim. Remember at Step 5 to write down the StatCrunch method you use.

Pearson Product-Moment Correlation Coefficient

Using the states Module 11 data test whether there is a relationship between the variable “sex” and the “Disp” score, alpha = .05.  Write the hypotheses. Show a scatterplot of the correlations between the two variables. Describe the direction and strength of the correlation. Report the results in APA format. Submit a copy of your SPSS output.

The States Module 11 Data Test

A cognitive psychologist studying motivation wants to determine if type of music has any effect on the number of days (in 1 month) participants visit a gym. A total of three gyms are selected that have different musical formats. 14 gym members are randomly sampled from each gym, and their gym attendance is monitored for 30 days. Complete the following ANOVA summary table, and use a significance level of α=0.05.

Use the =FDIST(F, dftreatment, dferror) function in Excel to locate the p-value for this ANOVA.

With the given significance level, what is the decision regarding the hypotheses?

• reject the null hypothesis
• fail to reject the null hypothesis

What would you conclude about these treatments?

• These data do not provide evidence of a difference between the treatments
• There is a significant difference between treatments