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Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 146432: A personnel manager is concerned about absenteeism. She decides to sample the records to determine if absenteeism is distributed evenly throughout the six-day workweek. The null hypothesis to be tested is: Absenteeism is distributed evenly throughout the week. The 0.01 level is to be used. The sample results are:
Day of the Week Number Absent
Monday 12
Tuesday 9
Wednesday 11
Thursday 10
Friday 9
Saturday 9
7. What is the expected frequency?
A. 9
B. 10
C. 11
D. 12
8. What is the calculated value of chi-square?
A. 1.0
B. 0.5
C. 0.8
D. 8.0
9. What is your conclusion?
A. Absenteeism is evenly distributed throughout the week.
B. Absenteeism is not evenly distributed throughout the week.
C. I cannot say anything about absenteeism based on my statistics.
D. Absenteeism is increasing throughout the week.
Click here to see answer by stanbon(26259)   |
Question 146436: Which of the following are true statements about the chi-square distribution?
A) Distribution is negatively skewed
B) Chi-square is based on two sets of degrees of freedom, one for the numerator and one for the denominator
C) Its shape is based on the degrees of freedom
D) All of the above are true
E) None of the above are true
Click here to see answer by stanbon(26259) |
Question 146435: A distributor of personal computers has five locations in the city. The sales in units for the first quarter of the year were as follows:
Location Observed Sales (Units)
North Side 70
Pleasantway 75
Southwyck 70
I-90 50
Venice Avenue 35
300
What is the critical value at the 0.01 level of risk?
A) 7.779
B) 15.033
C) 13.277
D) 5.412
E) None of the above
13. To analyze data cross-classified in a contingency table, how are the degrees of freedom found?
A) N-1
B) Rows - Columns
C) (Rows) x (Columns)
D) (Rows - 1) x (Columns - 1)
E) None of the above
14. The following table shows the adjustment to civilian life and place of residence.
Residence After Adjustment to Civilian Life
Release From Prison Outstanding Good Fair Unsatisfactory
Hometown 27 35 33 25
Not hometown 13 15 27 25
Total 40 50 60 50
What is the critical value for this contingency table at the 0.01 level of significance?
A) 9.488
B) 2.070
C) 11.345
D) 13.277
E) None of the above
15. The educational level and the social activity of a sample of executives follow.
Social Activity
Education Above Average Average Below Average
College 30 20 10
High School 20 40 90
Grade School 10 50 130
What does the expected frequency for the "above average" social activity and "high school" education equal?
A) 9.50 D) 28.50
B) 60.00 E) None of the above
C) 22.50
Click here to see answer by stanbon(26259) |
Question 146434: Two chi-square distributions were plotted on the same chart. One distribution was for 3 degrees of freedom and the other was for 12 degrees of freedom. Which distribution would tend to approach a normal distribution?
A)3 degrees
B) 12 degrees
C) 15 degrees
D) All would
E) None of the above
Click here to see answer by stanbon(26259) |
Question 146428: In a three-digit lottery, each of the three digits is supposed to have the same probability of occurrence
(counting initial blanks as zeros, e.g., 32 is treated as 032). The table shows the frequency
of occurrence of each digit for 90 consecutive daily three-digit drawings. (a) Make a bar chart and
describe it. (b) Calculate expected frequencies for each class. (c) Perform the chi-square test for a
uniform distribution. At α = .05, can you reject the hypothesis that the digits are from a uniform
population? Lottery3
Digit Frequency
0 33
1 17
2 25
3 30
4 31
5 28
6 24
7 25
8 32
9 25
Total 270
Click here to see answer by stanbon(26259) |
Question 146430: Recently, students in a marketing research class were interested in the driving behavior of students. Specifically, the marketing students were interested if exceeding the speed limit was related to gender. They collected the following responses from 100 randomly selected students:
Speeds Does not speed
Males 40 25
Females 10 25
1. The appropriate test to analyze the relationship between gender and education is:
A. regression analysis
B. Analysis of variance
C. Contingency table analysis
D. Goodness-of-fit
2. The null hypothesis for the analysis is:
A. There is no relationship between gender and speeding.
B. The correlation between gender and speeding is zero.
C. As gender increases, speeding increases.
D. The mean of gender equals the mean of speeding.
3. The degrees of freedom for the analysis is:
A. 1
B. 2
C. 3
D. 4
4. Using 0.05 as the significance level, what is the critical value for the test statistic?
A. 9.488
B. 5.991
C. 7.815
D. 3.841
5. What is the value of the test statistic?
A. 100
B. 9.89
C. 50
D. 4.94
6. Based on the analysis, what can be concluded?
A. Gender and speeding are correlated.
B. Gender and speeding are not related.
C. Gender and speeding are related.
D. No conclusion is possible.
Click here to see answer by stanbon(26259) |
Question 146423: A certain airplane has two independent alternators to provide electrical power. The probability that a given alternator will fail on a 1-hour flight is .02. What is that (a) both will fail (b) Neither will fail? (c) One or the other will fail? Show all steps carefully?
Click here to see answer by stanbon(26259) |
Question 147139: The probability that San Franciso plays in the next Super Bowl is nine times the probability that they do not play in the next Super Bowl. The propability that San Francisco plays in the next Super Bowl plus the probability that they do not play is 1. What is the probability that San francisco plays in the next Super Bowl?
Click here to see answer by mangopeeler07(450) |
Question 147378: Alan is jealous that his neighbor down the street has a very cool toy that he has been admiring for 20 years now. He decides to break in and steal it. He knows that the house is monitored by a security system that requires a 5digit pass code. He knows that it needs 2 digits and 3 letters. How many pass keys are there if no digits can be repeated?
Click here to see answer by vleith(1977) |
Question 147463: an auditor reviewed 25 oral surgery insurance claims form a particular surgical office, determining that the mean out-of-pocket patient billing above the reimbused amount was $275.66 with a standard deviation of $78.11. (a) At the 5 percent level of significance, does this sample prove a violation of the guideline that the average patient should pay no more than $250 out-of-pocket? State your hypotheses and decision rule. (b) Is this a close decision?
Click here to see answer by stanbon(26259) |
Question 147462: The Web-based company "Oh Baby! Gifts" has a goal of processing 95 percent of its orders on the same day they are recived. If 485 out of the next 500 orders are process on the same day, would this prove that they are exceeding their goal, using standard deviation of .025?
Click here to see answer by stanbon(26259) |
Question 147461: A coin was flipped 60 times and came up heads 38 times. (a)At the .10 level of significance, is the coin biased toward heads? Show your decision rule and calculations. (b) Calculate a p-value and interpret it.
Click here to see answer by stanbon(26259) |
Question 147460: Faced with the rising fax costs, a firm issued a guideline that transmission of 10 pages or more should be sent by 2-day mail instead. Exceptions are allowed, but they want the average to be 10 or below. The firm examined 35 randomly chosen fax transmissions during the next year, yielding a sample mean of 14.44 with a standard deviation 4.45 pages. (a). At the .01 level of significance, is the true mean greater that 10? (b) Use Excel to find the right-tail p-value.
Click here to see answer by stanbon(26259) |
Question 146629: 31. What can we conclude if the coefficient of determination is 0.94?
A) Strength of relationship is 0.94
B) Direction of relationship is positive
C) 94% of total variation in one variable is explained by variation in the other variable
D) All of the above are correct
E) None of the above is correct
Click here to see answer by nanaktutors@yahoo.com(8) |
Question 147829: Currently, Person A has $60 and Person B has $135. Person A decides to save $5 of his/her paycheck each week, while Person B decides to spend all of his/her paycheck and an additional $10 each week. How long will it be before Person A and Person B have the same amount of money? The following represents the situation:
Person A's Current Savings + 5 × Number of Weeks = Person B's Current Savings – 10 × Number of Weeks
Task:
A. Write an equation describing the situation in the Given.
B. Solve the equation written in A.
C. Using an appropriate technological tool of your choice, make a properly labeled graph of the situation. Is your solution from B correct? Explain your reasoning.
D. Based on your graph, what can you conclude about the difference in amounts of money each person has after week 5?
Click here to see answer by stanbon(26259) |
Question 147924: Just need some suggestions!!!!
Write a brief essay (suggested length of 2 pages) in which you:
A. Define the Law of Large Numbers, citing a credible source.
B. Explain the Law of Large Numbers in your own words using a coin toss as an example.
C. Apply the Law of Large Numbers
1. Using a coin toss and fictitious data, explain how the following scenario is possible: As the number of trials increases, the differences between the number of actual and expected successes tends to grow, but the difference between the percentage of actual and expected successes tends to decrease.
2. Explain your answer to the following question: Is it true that if I flip a coin 1,000 times I will get heads 500 times?
3. Explain your answer to the following question: Is it true that if I get tails 3 times in a row that my chances of getting heads on my next toss is greater than 50%?
Click here to see answer by stanbon(26259) |
Question 147922: A potato chip company packages its potato chips into 12.0 ounce bags. You find it hard to believe that the bag contains enough potato chips to weigh 12.0 ounces and would like to make an official complaint. Before doing so, you decide to run an experiment so that you can have some confidence that the company’s claim is incorrect. Over the next several months you buy 30 bags of potato chips and weigh the contents of each one. You discover that the mean weight is 11.9 ounces with a standard deviation of 0.4 ounces. You decide that you will only complain if you can be 95% sure that the bags do not contain at least 12.0 ounces of potato chips. You decide to construct a hypothesis test.
Task:
A. Determine if this is a one-tailed or two-tailed test. Justify your decision.
B. State the null hypothesis and alternative hypothesis. Your null hypothesis should assume the company’s claim is correct.
C. Define the term Type I error and explain what a Type I error is in terms of this problem.
D. Define the term level of significance and identify the level of significance for this problem.
E. Calculate the test statistic as a z-score. Show all relevant work.
F. Using a standard table, you determine that the critical value is –1.645. Determine if you are able to reject the null hypothesis and explain how you reached this conclusion. (Your conclusion should include a comment relating the results to the original problem.)
Click here to see answer by stanbon(26259) |
Question 147978This question is from textbook APPLIED STATISTICS IN BUSINESS AND ECONOMICS
: 12.48 In the following regression, X = weekly pay, Y = income tax withheld, and n = 35 McDonald’s employees. (a) Write the fitted regression equation. (b) State the degrees of freedom for a twotailed test for zero slope, and use Appendix D to find the critical value at α = .05. (c) What is your conclusion about the slope? (d) Interpret the 95 percent confidence limits for the slope. (e) Verify that F = t2 for the slope.
a) Write the fitted regression equation.
Y = 30.7963 + 0.0343X
--------------------------------
(b) State the degrees of freedom for a twotailed test for zero slope, and use Appendix D to find the critical value at α = .05.
df = 33 ; critical value is 2.035 (see page 782)
(c) What is your conclusion about the slope?
Since the p-value is 0.0068 (less than 1%), the true value is not zero.
------------------------
(d) Interpret the 95 percent confidence limits for the slope.
We are 95% confident that the slope is between 0.0101 and 0.0584
----------------------
(e) Verify that F = t2 for the slope.
2.889^2 = = 8.346321 (rounded is 8.35)
This question is from textbook APPLIED STATISTICS IN BUSINESS AND ECONOMICS
Click here to see answer by stanbon(26259) |
Question 147978This question is from textbook APPLIED STATISTICS IN BUSINESS AND ECONOMICS
: 12.48 In the following regression, X = weekly pay, Y = income tax withheld, and n = 35 McDonald’s employees. (a) Write the fitted regression equation. (b) State the degrees of freedom for a twotailed test for zero slope, and use Appendix D to find the critical value at α = .05. (c) What is your conclusion about the slope? (d) Interpret the 95 percent confidence limits for the slope. (e) Verify that F = t2 for the slope.
a) Write the fitted regression equation.
Y = 30.7963 + 0.0343X
--------------------------------
(b) State the degrees of freedom for a twotailed test for zero slope, and use Appendix D to find the critical value at α = .05.
df = 33 ; critical value is 2.035 (see page 782)
(c) What is your conclusion about the slope?
Since the p-value is 0.0068 (less than 1%), the true value is not zero.
------------------------
(d) Interpret the 95 percent confidence limits for the slope.
We are 95% confident that the slope is between 0.0101 and 0.0584
----------------------
(e) Verify that F = t2 for the slope.
2.889^2 = = 8.346321 (rounded is 8.35)
This question is from textbook APPLIED STATISTICS IN BUSINESS AND ECONOMICS
Click here to see answer by assante10(1) |
Question 147977: 12.48 In the following regression, X = weekly pay, Y = income tax withheld, and n = 35 McDonald’s employees. (a) Write the fitted regression equation. (b) State the degrees of freedom for a twotailed test for zero slope, and use Appendix D to find the critical value at α = .05. (c) What is your conclusion about the slope? (d) Interpret the 95 percent confidence limits for the slope. (e) Verify that F = t2 for the slope.
Click here to see answer by stanbon(26259) |
Question 147826: A potato chip company packages its potato chips into 12.0 ounce bags. You find it hard to believe that the bag contains enough potato chips to weigh 12.0 ounces and would like to make an official complaint. Before doing so, you decide to run an experiment so that you can have some confidence that the company’s claim is incorrect. Over the next several months you buy 30 bags of potato chips and weigh the contents of each one. You discover that the mean weight is 11.9 ounces with a standard deviation of 0.4 ounces. You decide that you will only complain if you can be 95% sure that the bags do not contain at least 12.0 ounces of potato chips. You decide to construct a hypothesis test.
Task:
A. Determine if this is a one-tailed or two-tailed test. Justify your decision.
B. State the null hypothesis and alternative hypothesis. Your null hypothesis should assume the company’s claim is correct.
C. Define the term Type I error and explain what a Type I error is in terms of this problem.
D. Define the term level of significance and identify the level of significance for this problem.
E. Calculate the test statistic as a z-score. Show all relevant work.
F. Using a standard table, you determine that the critical value is –1.645. Determine if you are able to reject the null hypothesis and explain how you reached this conclusion. (Your conclusion should include a comment relating the results to the original problem.)
Click here to see answer by stanbon(26259) |
Question 147923: Just need some suggestions!!!!
Write a brief essay (suggested length of 2 pages) in which you:
A. Explain why random samples are preferred to nonrandom samples.
B. Describe the advantages and limitations of the following commonly used sampling techniques:
1. Simple random sampling
2. Stratified sampling
3. Cluster sampling
4. Multi-stage sampling
Click here to see answer by stanbon(26259) |
Question 148132: By using a ruler, you determine that the distance between two cities on a map is 3.4 inches. According to the map’s scale, 2 inches represents 75 miles. What is the actual distance between the two cities?
Task:
Write an essay (suggested length of 1 page) in which you communicate mathematical information in written form. Include the following:
A. Briefly explain the general procedure used to identify and set up a proportion problem.
B. Write a proportion that correctly represents the problem in the Given.
1. Solve the proportion, showing all relevant work.
C. Explain the reasoning behind the equation you set up (e.g., how did you determine the two ratios in the problem, and how do you know if they are equivalent?).
D. Explain each step used to solve the equation. Your explanation should include the original equation, the equation at each step, and the final equation with the unknown equal to some number. (Use complete sentences, not mathematical symbols, to explain the steps.)
E. Briefly explain (in 1–2 sentences) what the answer means in terms of the original problem.
Click here to see answer by stanbon(26259) |
Question 148409This question is from textbook
: the probability that San Francisco plays in the next Super Bowl is nine times the probability that they do not play in the next Super Bowl. The probability that San Francisco plays in the next Super Bowl plus the probabilty that they do not play is 1. What is the probablity that San Francisco plays in the next Super Bowl?This question is from textbook
Click here to see answer by stanbon(26259) |
Question 148331This question is from textbook
: Probability is not my high point. I have tried to come up with an answer, but I need assistance, please. Here is the question:
A sample of 20 pages was taken without replacement from the 1,591-page phone directory
Ameritech Pages Plus Yellow Pages. On each page, the mean area devoted to display ads was measured (a display ad is a large block of multicolored illustrations, maps, and text). The data (in
square millimeters) are shown below:
0 260 356 403 536 0 268 369 428 536
268 396 469 536 162 338 403 536 536 130
(a) Construct a 95 percent confidence interval for the true mean.
(b) Why might normality be an issue here?
(c) What sample size would be needed to obtain an error of ±10 square millimeters with 99 percent confidence?
(d) If this is not a reasonable requirement, suggest one that is.
Thank you!This question is from textbook
Click here to see answer by stanbon(26259) |
Question 148687: Biting an unpopped kernel of popcorn hurts! As an experiment, a self-confessed connoisseur of cheap popcorn carefully counted 773 kernels and put them in a popper. After popping, the unpopped kernels were counted. There were 86. (a) Construct a 90 percent confidence interval for the proportion of all kernels that would not pop. (b) Check the normality assumption. (c) Try the Very Quick Rule. Does it work well here? Why, or why not? (d) Why might this sample not be typical?
Click here to see answer by stanbon(26259) |
Question 148467: In a bumper test, three types of autos were deliberately crashed into a barrier at 5 mph, and the
resulting damage (in dollars) was estimated. Five test vehicles of each type were crashed, with
the results shown below. Research question: Are the mean crash damages the same for these three
vehicles? Crash1Crash Damage ($)
Goliath Varmint Weasel
1,600 1,290 1,090
760 1,400 2,100
880 1,390 1,830
1,950 1,850 1,250
1,220 950 1,920
Click here to see answer by stanbon(26259) |
Question 148777This question is from textbook Understanding Basic Statistics
: Does anyone out there is statistics land have a clue how to figure this problem out??? I would appreciate any help. Thank you in advance!
At wind speeds above 1000 cm/sec, significant sand-moving events begin to occur. Wind speeds below 1000 cm/sec deposit sand and wind speeds above 1000 cm/sec move sand to new locations. The cyclic nature of wind and moving sand determines teh shape and location of large dunes. At a test site, the prevailing direction of the wind did not change noticeably. However, the velocity did change. Sixty wind speed readings gave an average velocity of x(bar)=1075 cm/sec. Based on long term experience, sigma (standard deviation)can be assumed to be 265 cm/sec.
Find a 95% confidence interval for the population mean wind speed at this site AND does the confidence interval indicate that the population mean wind speed is such that the sand is always moving at this site. Explain.This question is from textbook Understanding Basic Statistics
Click here to see answer by stanbon(26259) |
Question 148808: The mean weight of newborn infants at a community hospital is 6.6 pounds. A sample of seven infants is randomly selected and their weights at birth are recorded as 9.0, 7.3, 6.0, 8.8, 6.8, 8.4, and 6.6 pounds.
Click here to see answer by stanbon(26259) |
Question 148815This question is from textbook Understanding Basic Statistics
: Please Help!
The home run percentage is the number of home runs per 100 times at bat. A random sample of 43 professional baseball players gave the following data for home run percentages. x(bar)=2.29 and s=1.40.
Compute a 99% CI for the population mean of home run percentages for all professional baseball players AND: The home run percentages for 3 professional players are:
Tim Huilett, 2.5 Herb Hunter, 2.0 Jackie Jensen, 3.8
Examine your CI's and describe how home run percentages for these players compare to the population average.This question is from textbook Understanding Basic Statistics
Click here to see answer by stanbon(26259) |
Question 148859: Greetings,
Statistics question. questeion posed by an English as a second language statistics intructor.
2) Can the bell shaped curve on the graph of normal distribution cross the x-axis? Explain your answer.
Thanks for the help,
Dennis Wade
Click here to see answer by stanbon(26259) |
Question 148919: Are the answers right?
University of Phoenix Material
Parametric and Nonparametric Data Identification Assignment
Label each of the following situations “P” if it is an example of parametric data or “NP” if it is an example of nonparametric data.
1. A manufacturer produces a batch of memory chips (RAM) and measures the mean-time-between-failures (MTBF). The manufacturer then changes a manufacturing process and produces another batch and again measures the MTBF. Did the change to the process improve the MTBF? P____
2. From a written survey where the respondents were asked to rate an individual on a scale of 1 to 5, one group rated an individual a 3.7, another group rated the individual a 4.3. Is the difference statistically significant? __NP__
3. A catering company is buying equipment in order to set up their own store. They have a choice of two ovens that they can purchase for the store. The used oven is $100 less than the new oven, but its heating calibration is off by 20 degrees. Which one is a better buy for them? P____
4. Jim Smith owns three real estate offices in Anytown. He has decided to open one more office, but he cannot decide between Hometown or Uptown as the town where he wants to locate. He will be comparing the mean number of homes sold per real estate agent, and the mean commission percentage earned by agents in the two towns to make his decision. _P___
5. A study to determine if job absenteeism is distributed evenly over the week. __NP__
6. Mel’s Diner has been surveying their customers for the past couple of years about their dining experience in the restaurant. The survey uses a scale of one to five, five being best to indicate customer satisfaction. Mel’s customer satisfaction averaged 2.5 last year, but this year it is 2.9. Is this difference statistically significant? _NP___
7. Sally’s Beauty Salon just opened for business. Sally assigns the stylists customers on a rotation basis so that everyone is kept busy all day. One month after she opened the salon, Sally’s customer count for each stylist was (a) 20 customers; (b) 30 customers; (c) 15 customers; and (d) 25 customers. Has Sally been fair in how she allocates customers to each of the stylists? _P___
8. A comparison of salaries between male and female employees in the same organization. _NP___
Click here to see answer by stanbon(26259) |
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