Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 134267: Please assist, No ISBN number due to being an online course.
An expert in a case alleged racial discrimination in a state university school of nursing introduced a regression of the determination of Salary of each professor for each year during an 8-year period (n=423) with the following results, with dependent variable Year (year in which the salary was observed) and predictors YearHire (year when the individual was hired), Race (1 if individual is black, 0 otherwise), and Rank (1 if individual is an assistant professor, 0 otherwise).
Interpret these results
Variable=Intercept, Coefficient= -3,816,521, t= -29.4, p= .000
Variable=Year, Coefficient= 1,948, t= 29.8, p= .000
Variable=Year/Hire, Coefficient= -826, t= -5.5, p= .000
Variable=Race, Coefficient= -2,093, t= -4.3, p= .000
Variable=Rank, Coefficient= -6,438, t= -22.3, p= .000
R2=0.811, R2adj=0.809, s=3,318
Thank you
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Question 134149: 38. The accounting department at Weston Materials, Inc., a national manufacturer of unattached garages, reports that it takes two construction workers a mean of 32 hours and a standard deviation of 2 hours to erect the Red Barn model. Assume the assembly times follow the normal distribution.
a. Determine the z values for 29 and 34 hours. What percent of the garages take between 32 hours and 34 hours to erect?
b. What percent of the garages take between 29 hours and 34 hours to erect?
c. What percent of the garages take 28.7 hours or less to erect?
d. Of the garages, 5 percent take how many hours or more to erect?
44. The number of passengers on the Carnival Sensation during one-week cruises in the Caribbean follows the normal distribution. The mean number of passengers per cruise is 1,820 and the standard deviation is 120.
a. What percent of the cruises will have between 1,820 and 1,970 passengers?
b. What percent of the cruises will have 1,970 passengers or more?
c. What percent of the cruises will have 1,600 or fewer passengers?
d. How many passengers are on the cruises with the fewest 25 percent of passengers?
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Question 133946: You are the incoming inspector for potato chips – you are to ensure that each bag has 16 ounces or more in it. You want your testing to be at the level of significance of 0.05. You pull a sample of 49 bags of chips from a recent truckload. Your sample statistics are:
x-bar (the sample mean) = 15.9 ounces
s ( the sample standard deviation) = 0.35 ounces
(a) what is the null and alternative hypothesis
(b) one or two tailed test ??
(c) what is the critical z value for your test at the 0.05 level of significance??
(d) what is the calculated z value ??
(e) what is your decision about the load of potato chips ??
-- reject ?? -- not-reject ??
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Question 134449: I'm sorry there is no ISBN #, this is from an on line class and I am lost! Thank you for your help.
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.
Need to do the following:
Determine if this is a one or two-tailed test and justify why
State the NULL hypothesis (assuming the company's claims are correct) and alternative hypothesis
Explain Type I error in relation to this problem
Explain Level of Significance in relation to this problem
Calculate the test statistic as a Z score and show relevant work
Use standard table, determine critical value is -1.645. Determine if you are able to reject the null hypothesis, explain how you came to that conclusion
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Question 134510: Please can someone help me? My homework is due soon and I am not sure what to do. These are my last two questions.
1) The probability that federal income tax returns will have 0,1, or two errors is 0.53,0.15, and 0.3 respectively. If 10 randomly selected returns are audited, what is the probablity that six will have no errors, three will have one error, and one will have two errors?
A)0.184
B) 0.127
C) 0.020
D) 0.035
2) The probability that a person will have 0,1,or two dental checkups per year is 0.2,0.5, and 0.3 respectively. If seven people are picked at random, what is the probablity that two will have no checkup, four willl have one checkup and one will have two checkups in the next year?
A) 0.079
B) 0.013
C) 0.008
D) 0.043
Any and all help will be greatly appreciated. I am not sure at all how to approach these questions and to be honest, I really don't understand them.
Click here to see answer by stanbon(26259) |
Question 134429: You are the Vice President for Human Resources at XYZ Investment Management, Inc. Your employees have recently complained about their long working hours. You collected a sample of 25 weekly timesheets and calculated an average of 41.5 hours with a standard deviation of 2.5 hours.
Over lunch, you discuss this problem with your long-time college friend working for Bayview Financial. She points out that in her company, the employees work an average of 42 hours. The data that she recently collected included timesheets for 35 employees. She calculated a standard deviation of 3.
1. Which test do you have to use in order to answer the question: “Do the employees at XYZ Investment Management on average work fewer hours than the employees at Bayview Financial?”
Please circle the correct answer:
A. Two-sample test of means (large sample)
B. Two-sample test of means (small sample)
C. T-test of one mean
D. Two sample test of proportions
2. Please state your hypotheses, H0 and Ha, and perform the hypothesis test using the 5-step testing procedure [alpha = 0.05].
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Question 134428: 15.28 Can people really identify their favorite brand of cola? Volunteers tasted Coca-Cola Classic, Pepsi, Diet Coke, and Diet Pepsi, with the results shown below. Research question: At a = .05, is the correctness of the prediction different for the two types of cola drinkers? Since it is a 2 x 2 table, try also a two-tailed two-sample z test for π1 = π2 and verify that z˛ is the same as your chi-square statistic.
Correct? Regular Diet Row Total
Yes 7 7 14
No 12 20 32
Total 19 27 46
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Question 134515This question is from textbook Applied Statistics in Business and Economics
: 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? Crash1
Crash 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
This question is from textbook Applied Statistics in Business and Economics
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Question 134516This question is from textbook Applied Statistics in Business and Economics
: Does lovastatin (a cholesterol-lowering drug) reduce the risk of heart attack? In a Texas study, researchers gave lovastatin to 2,325 people and an inactive substitute to 2,081 people (average age 58). After 5 years, 57 of the lovastatin group had suffered a heart attack, compared with 97 for the inactive pill. (a) State the appropriate hypotheses. (b) Obtain a test statistic and p-value. Interpret the results at α = .01. (c) Is normality assured? (d) Is the difference large enough to be important? (e) What else would medical researchers need to know before prescribing this drug widely? (Data are from Science News 153 [May 30, 1998], p. 343.)This question is from textbook Applied Statistics in Business and Economics
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Question 134527: I really need help with these two questions. I am not sure if I have been overworking myself but, I don't know what to do anymore with them. Help!!!
1) On a Saturday evening, 34% of the people in chicago go out to dinner, 18% see a movie, 13% have a party, and 35% stay home. If seven people are randomly selected, what is the probability that one eats out, three see a movie, two have a party and one stays home?
A) 0.099
B) 0.459
C) 0.102
D) 0.0049
2) A package of 10 batteries is checked to determine if there are any dead batteries. Four batteries are checked. If one or more are dead, the package is not sold. What is the probability that the package will not be sold if there are actually three dead batteries in the package?
A) 2/3
B) 6/7
C) 5/6
D) 4/5
Thank you for any help that you can give me. I am just not "getting" this stuff.
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Question 134531: Can someone please help me to understand what to do with these two problems??? I am lost.
1) Give the variance of the following distribution.
X P(X)
0 0.20
1 0.35
2 0.10
3 0.25
4 0.10
A) 1.83
B) 1.31
C) 1.25
D) 1.71
2) What is the standard deviation of the following probability distribution?
X P(X)
0 0.20
2 0.05
4 0.35
6 0.25
8 0.15
A) 2.6
B) 4.7
C) 5.4
D) 3.9
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Question 134555: I have a couple questions here that I do not understand how to do. Can someone please give me some guidance on how to do them?
1) A box contains blue chips and red chips. A person selects two chips without replacement. If the probability of selecting a blue chip and a red chip is 32/128, and the probability of selecting a blue chip on the first draw is 5/16, find the probability of selecting the red chip on the second draw, given the first chip selected was a blue chip?
a) 1/5
b) 2/5
c)3/5
d) 4/5
2) A recent poll by the American automobile club found that 30% of those surveyed are worried about aggressive drivers on the road. If three people are selected at random, what is the probability that all three will be worried about agressive drivers on the road?
a) .900
b) 0.027
c) 0.081
d) 0.300
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Question 134581This question is from textbook Pre-Algebra
: (This is a combination formula not a permutation)A radio station takes the names of the first 20 listeners who call in after hearing a certain song.The station will randomly select 3 of the callers to win tickets to a concert.If 3 friends are among the first 20 callers, what is the probability that the 3 friends will win tickets?
1)how many possible combinations of 3 callers can be selected to win tickets?
2)How many possible combinations of 3 ticket winners include all 3 of the friends?
3)Find the probability that the 3 friends win tickets.This question is from textbook Pre-Algebra
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Question 134667: I need some help please, I've searched the website and I'm not finding this answer. NO ISBN as I'm in an online class.
Biting an un-popped 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 un-popped 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?
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Question 134684: Hello, Can someone show me how to work this problem. I'm trying and cannot seem to figure this out. Thanks in Advance.
The Web-based company Oh Baby! Gifts has a goal of processing 95 percent of its orders on the same day they are received. If 485 out of the next 500 orders are processed on the same day, would this prove that they are exceeding their goal, using a = .025? (See story.news.yahoo.com accessed June 25, 2004.)
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Question 134678: 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.
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Question 134747: 15.18 Sixty-four students in an introductory college economics class were asked how many credits they had earned in college, and how certain they were about their choice of major. Research question: At α = .01, is the degree of certainty independent of credits earned? Certainty
Credits Earned Very Uncertain Somewhat Certain Very Certain Row Total
0–9 12 8 3 23
10–59 8 4 10 22
60 or more 1 7 11 19
Col Total 21 19 24 64
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Question 134751: the telephone extensions at a company use 4 digits
a. how many extensions are possible if there no restrictions?
b. how mant extensions are possible if the first digit cannot be 0 or 9?
c. how many extensions are possible if the first digit can only be 1?
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Question 134751: the telephone extensions at a company use 4 digits
a. how many extensions are possible if there no restrictions?
b. how mant extensions are possible if the first digit cannot be 0 or 9?
c. how many extensions are possible if the first digit can only be 1?
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Question 134254: Need of help, I do not have an ISBN number due to being an online course.
A researcher used stepwise regression to create regression models to predict birth rate (births per 1,000) using five predictors: LifeExp (life expectancy in years), InfMort (infant mortality rate), Density (population density per squre kilometer) GDPCap (Gross Domestic Product per capita), and Literature (Literacy Percent). Interpret these results.
153 observations; BirthRate is the Dependent Variable
p-values for the coefficients
Nvar:
1)LifeExp=0,InfMort=.0000,Density=0,GDPCap=0,Literate=0,
s=6.318,AdjR=.722,R=.724
2)LifeExp=0,InfMort=.0000,Density=0,GDPCap=0,Literate=.0000,
s=5.334,AdjR=.802, R=.805
3)LifeExp=0,InfMort=.0000,Density=0,GDPCap=.0242,Literate=.0000,
s=5.21,AdjR=.807,R=.811
4)LifeExp=.5764,InfMort=.0000,Density=0,GDPCap=.0311,Literate=.0000,
s=5.273,AdjR=.806,R=.812
5)LifeExp=.5937,InfMort=.0000,Density=.6289,GDPCap=.0440,Literate=.0000,
s=5.287,AdjR=.805,R=.812
Thank you!
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Question 134148: 66. A survey of undergraduate students in the School of Business at Northern University revealed the following regarding the gender and majors of the students:
Major
Gender
Accounting
Management
Finance
Total
Male
100
150
50
300
Female
100
50
50
200
Total
200
200
100
500
a. What is the probability of selecting a female student?
b. What is the probability of selecting a finance or accounting major?
c. What is the probability of selecting a female or an accounting major? Which rule of addition did you apply?
d. Are gender and major independent? Why?
e. What is the probability of selecting an accounting major, given that the person selected is a male?
f. Suppose two students are selected randomly to attend a lunch with the president of the university. What is the probability that both of those selected are accounting majors?
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Question 134147: 8. A sample of 2,000 licensed drivers revealed the following number of speeding violations.
Number of Violations
Number of Drivers
0
1,910
1
46
2
18
3
12
4
9
5 or more
5
Total
2,000
a. What is the experiment?
b. List one possible event.
c. What is the probability that a particular driver had exactly two speeding violations?
d. What concept of probability does this illustrate?
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Question 134146: Please help
68. The American Automobile Association checks the prices of gasoline before many holiday weekends. Listed below are the self-service prices for a sample of 15 retail outlets during the May 2003 Memorial Day weekend in the Detroit, Michigan, area.
1.44
1.42
1.35
1.39
1.49
1.49
1.41
1.46
1.41
1.49
1.45
1.48
1.39
1.46
1.44
70. A recent article suggested that if you earn $25,000 a year today and the inflation rate continues at 3 percent per year, you'll need to make $33,598 in 10 years to have the same buying power. You would need to make $44,771 if the inflation rate jumped to 6 percent. Confirm that these statements are accurate by finding the geometric mean rate of increase.
72. The weights (in pounds) of a sample of five boxes being sent by UPS are: 12, 6, 7, 3, and 10.
a. Compute the range.
b. Compute the mean deviation.
c. Compute the standard deviation.
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Question 134145: 62. The Citizens Banking Company is studying the number of times the ATM located in a Loblaws Supermarket at the foot of Market Street is used per day. Following are the numbers of times the machine was used over each of the last 30 days. Determine the mean number of times the machine was used per day
83
64
84
76
84
54
75
59
70
61
63
80
84
73
68
52
65
90
52
77
95
36
78
61
59
84
95
47
87
60
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Question 133924: Can someone please help me with these two questions? I am having a difficult time and am not sure what to do.
1) The probability that federal income tax returns will have 0,1,or 2 errors is 0.53,0.15, and 0.32 respectively. If 10 randomly selected returns are audited, what is the probability that six will have no errors, three will have one error, and one will have two errors?
2) The probability that a person will have 0,1, or 2 dental checkups per year is 0.2, 0.5, and 0.3 respectively. If seven people are picked at random, what is the probability that two will have no checkup, four will have one checkup and one will have two checkups in the next year.
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Question 133847: A box contains blue chips and red chips. A person selects two chips without replacement. If the probability of selecting a blue chip and a red chip is 32/128, and the probability of selecting a blue chip on the first draw is 5/16, find the probability of selecting a red chip on the second draw, given that the first chip selected was a blue chip.
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Question 133843: A nursery has 8 different plants, 5 different baskets, and 6 different ribbions. If Ignacio wins a plant from the nursery, what is the probability that he well get a fuchsia in a round basket with a pink ribbon?
A. 1/19
B. 1/40
C. 1/48
D. 1/240
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Question 134816: Please and thank you in advance, I'm an online student, so there is no text book. How do I work this problem, what formula do I use? Thanks, your the best.
Faced with rising fax costs, a firm issued a guideline that transmissions 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 of 4.45 pages.
(a) At the .01 level of significance, is the true mean greater than 10?
(b) Use Excel to find the right-tail p-value.
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Question 134817: Hi, I'm an online student with no physical textbook and the online textbook sucks, please help. Wish I could sit down with you and work these so you could explain it to me. I'm just lost with Statistics all together. Thanks for your help.
In Dallas, some fire trucks were painted yellow (instead of red) to heighten their visibility. During a test period, the fleet of red fire trucks made 153,348 runs and had 20 accidents, while the fleet of yellow fire trucks made 135,035 runs and had 4 accidents. At α = .01, did the yellow fire trucks have a significantly lower accident rate?
(a) State the hypotheses.
(b) State the decision rule and sketch it.
(c) Find the sample proportions and z test statistic.
(d) Make a decision.
(e) Find the p-value and interpret it.
(f ) If statistically significant, do you think the difference is large enough to be important? If so, to whom, and why?
(g) Is the normality assumption fulfilled? Explain.
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Question 134849: I'm an online student, please help.
A manufacturer claims that at least 99% of all his products meet the minimum government standards. A survey of 500 products revealed ten did not meet the standard.
Conduct the 5-step hypothesis test … and answer the following:
What is the null hypothesis?
What is the alternate hypothesis?
What is the critical value if a = .01?
What is the z-statistic? ?
What is your decision ?? Do the products meet the government standards?
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