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Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 130726: Please help me. I am stuck with this question.
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 α = .05, is the correctness of the prediction different for the two types of cola drinkers? Could you identify your favorite brand in this kind of test? Since it is a 2 × 2 table, try also a two-tailed two-sample z test for π1 = π2 and verify that z2 is the same as your chi-square statistic.Which test do you prefer? Why?
Correct? Regular Cola Diet Cola Row Total
Yes, got it right 7 7 14
No, got it wrong 12 20 32
Col Total 19 27 46
Thank you kindly.
Click here to see answer by stanbon(26259)   |
Question 130725: Please help me. I need your help with this question.
Thank you kindly.
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?
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
Click here to see answer by stanbon(26259) |
Question 131651: 11.23 Mean output of solar cells of three types are measured six times under random light intensity over a period of 5 minutes, yielding the results shown. Research question: Is the mean solar cell output the same for all cell types?
SolarWatts
Solar Cell Output (watts)
Cell Type Output (watts)
A 123 121 123 124 125 127
B 125 122 122 121 122 126
C 126 128 125 129 131 128
Click here to see answer by stanbon(26259) |
Question 131678: Please help me. I am stuck with this question.
In a study of childhood asthma, 4,317 observations were collected on education and smoking during pregnancy, shown in the 4 x 3 contingency table below. At = .01, is smoking during pregnancy independent of education level? You can use any method you like to solve the problem, but please include hypotheses, critical value, value of the test statistic, p-value, and conclusion.
Education (below) No smoking < Half pack =or> Half Pack
< high school 641 196 196
High school 1,370 290 270
Some college 635 68 53
College 550 30 18
Thank you for your kind help
Click here to see answer by stanbon(26259) |
Question 131650: 10.64 A cognitive retraining clinic assists outpatient victims of head injury, anoxia, or other conditions that result in cognitive impairment. Each incoming patient is evaluated to establish an appropriate treatment program and estimated length of stay. To see if the evaluation teams are consistent, 12 randomly chosen patients are separately evaluated by two expert teams (A and B) as shown. At
the .10 level of significance, are the evaluator teams consistent in their stimates? State your hypotheses and show all steps clearly.
Estimated Length of Stay in Weeks
Patient
Team 1 2 3 4 5 6 7 8 9 10 11 12
A 24 24 52 30 40 30 18 30 18 40 24 12
B 24 20 52 36 36 36 24 36 16 52 24 16
Click here to see answer by stanbon(26259) |
Question 131715: This is not in a textbook. Can you help?
The owner of a car dealership wants to determin whether there is a relation between the income level and the type of vehicle purchased in their dealership. He randomly sampled 500 car buyers and obtained the folliwing data:
Income level SUV/minivan Midsize compact
0-$30K 13 71 106
$30-$60K 33 76 45
$60-+ 66 59 31
At the .05 level of significance determin whether there is a relation between the income level and the type of vehicl purchased.
Click here to see answer by stanbon(26259) |
Question 131792: Audiocasette tapes cost 4 dollars each and compact discs cost 12 dollars each. If the number of audiocasette tape was 3 more than twice the number of compact discs and if a total of $92 was spent, how many audiocasette tapes and how many compact discs were purchased?
Click here to see answer by checkley71(8405) |
Question 132049: College Admissions:
Hi, I am looking to get into an impacted program. The schools that offer it have, on average, 300 qualified applicants for 60 slots. All 300 qualifying applications go into a lottery.
If I manage to become one of these 300 qualified applicants, and I apply at 5 schools, all of which use the same process to distribute the slots (same availability of slots, same number of qualifying applications), what is my chance of getting into the program at one of these schools in percent?
Can someone show me how to work this out?
Many thanks in advance! You're work is highly appreciated!
Click here to see answer by edjones(3291)  |
Question 132069: There are 20 questions in a multiple-choice test. Each question has five choices and one correct answer out of these five choices. A student did not study. He/she answers the questions at random What are the probabilities that he/she makes (i) more than 10-answers right? (ii) exatly eight right? And (iii) at most 7 right?
Click here to see answer by stanbon(26259) |
Question 132311: In a bumper test, three types of autos were deliberately crashed into a barrier at 5 mph, and the resulting damage (in dollars) was estimated. Five test vehicles of each type were crashed, with the results shown below. Research question: Are the mean crash damages the same for these three vehicles?
Crash Damage ($)
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
----- ---- -----
6,410-6,880-8190
ANSWER IS NO THE TOTAL COSTS AS WELL AS THE AVERAGE COSTS ARE NOT THE SAME.
Click here to see answer by checkley71(8405) |
Question 132363: Please help me. I need answer to this question desperately. Please kindly help me.
a) Plot the data on U.S. general aviation shipments. (b) Describe the pattern and discuss possible causes. (c) Would a fitted trend be helpful? Explain. (d) Make a similar graph for 1992–2003 only. Would a fitted trend be helpful in making a prediction for 2004? (e) Fit a trend model of your choice to the 1992–2003 data. (f) Make a forecast for 2004, using either the fitted trend model or a judgment forecast. Why is it best to ignore earlier years in this data set? Airplanes
U.S. Manufactured General Aviation Shipments, 1966–2003
Year Planes
1966 15,587
1967 13,484
1968 13,556
1969 12,407
1970 7,277
1971 7,346
1972 9,774
1973 13,646
1974 14,166
1975 14,056
1976 15,451
1977 16,904
1978 17,811
1979 17,048
1980 11,877
1981 9,457
1982 4,266
1983 2,691
1984 2,431
1985 2,029
1986 1,495
1987 1,085
1988 1,143
1989 1,535
1990 1,134
1991 1,021
1992 856
1993 870
1994 881
1995 1,028
1996 1,053
1997 1,482
1998 2,115
1999 2,421
2000 2,714
2001 2,538
2002 2,169
2003 2,090
Click here to see answer by stanbon(26259) |
Question 132455: You need a wrench, a hammer, and a saw to complete a project. The hardware store has three different types of wrenches, four different types of hammers, and two different types of saws that will suffice. How many ways can you select the three tools you need?
Click here to see answer by stanbon(26259) |
Question 132454: Suppose it will rain on any given day eith the probability of 0.34, independent of everything. What is the probability that of three consecutive days it will rain on the first two and not rain on the third?
Click here to see answer by ilana(236) |
Question 132490: find the probability of winning the lottery according to the given rules. assume the numbers are selected at random.
you must correctly select 3 numbers, each from 0 to 9. the order of numbers is important.
Click here to see answer by stanbon(26259) |
Question 132469: Please help with this question, it is an online course so I don't have an ISBN number.
A sample of 25 concession stand purchases at the October 22 matinee of Bride of Chucky showed a mean purchase of $5.29 with a standard deviation of $3.02. For the October 26 evening showing of the same movie, for a samle of 25 purchases the mean was $5.12 with a standard deviation of $2.14 the means appear to be very close but not the variances. At alpha=.05, is there a difference in variances? Show an illustration of the decision rule. thank you!
Click here to see answer by stanbon(26259) |
Question 132260: Your help will be appreciated, I do not have an ISBN number because it's an online course:
To test the hypothesis that students who finish an exam first get better grades, Professor Hardtack kept track of the order in which papers were handed in. The first 25 papers showed a mean score of 77.1 with a standard diviation of 19.6 while the last 24 papers handed in showed a mean score of 69.3 with a standard deviation of 24.9. Is this a significant difference at alpha=.05? (a) state the hypotheses for a right tailed test. (b) obtain a test statistic and p-value assuming equal variances.interpret these results. (c) is the difference in mean scores large enough to be important? (d) is it reasonable to assume equal variances? (e) carry out a formal test for equal variances at alpha=.05. show all steps cleary.
Click here to see answer by stanbon(26259) |
Question 132571: How do I draw a tree to show?
(in a jar there are 2 red balls, 3 white balls and 1 green ball).
1.)What is the probability that a red ball will be drawn at 1st pick?
2.)What is the probability that a white ball will be drawn at 2nd pick?
Click here to see answer by stanbon(26259) |
Question 132572: Suppose that 78% of all Americans support a proposed law to require a police permit before someone is allowed to buy a gun. If a simple random sample of 45 Americans is to be taken, and each person is asked if they support the proposed law, and the sample proportion who do favor such a law is calculated:
a.Specify the sampling distribution of the sample proportion.
b.What is the probability that the sample proportion exceeds 80%?
Thanks For any help with this
Click here to see answer by stanbon(26259) |
Question 132638: Suppose that the time, X, that a tourist must wait to board a trolley car in San Francisco is a uniformly distributed random variable over the interval from 0 minutes to 10 minutes.
a.What is the probability that the tourist’s wait-time is exactly 0 minutes?
b.What is the probability that a tourist must wait longer than 8 minutes to board the trolley car?
c.What is the expected wait-time for a tourist?
Click here to see answer by stanbon(26259) |
Question 132633: Suppose that the weights of 10-week old kittens follow a normal distribution, with a mean value of 25 ounces and a standard deviation of 4 ounces. If a kitten’s weight is in the bottom 10% of the distribution of weights, then it is said to be undernourished. What is the cutoff weight for an undernourished kitten?
Click here to see answer by stanbon(26259) |
Question 132664: Year January Inflow February Inflow
1976 2.89 2.45
1977 3.57 2.57
1978 4.18 3.17
1979 4.71 3.93
1980 4.12 2.93
Using Feb. Inflow as the dependent variable and Jan. Inflow as the dependent variable.
What is the equation of the regression line?
What is the vaue of the coeifficent of determination.
What is the value of the linear correlation coeefficent.
Click here to see answer by stanbon(26259) |
Question 132539: Suppose that the weights of 10-week old kittens follow a normal distribution, with a mean value of 25 ounces and a standard deviation of 4 ounces. If a kitten’s weight is in the bottom 10% of the distribution of weights, then it is said to be undernourished. What is the cutoff weight for an undernourished kitten?
Click here to see answer by stanbon(26259) |
Question 132476: Suppose that the time, X, that a tourist must wait to board a trolley car in San Francisco is a uniformly distributed random variable over the interval from 0 minutes to 10 minutes.
a.What is the probability that the tourist’s wait-time is exactly 0 minutes?
b.What is the probability that a tourist must wait longer than 8 minutes to board the trolley car?
c.What is the expected wait-time for a tourist?
Click here to see answer by stanbon(26259) |
Question 132768: An auditor review 25 oral surgery insurance claims from a particular surgical office, determining that the mean out-of-pocket patient billing above the reimbursed amount of $275.66 with a standard deviation of $78.11.
a. At the 5% level of significance, does this sample prove 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 132780: 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 49 timesheets and calculated an average of 41.5 hours with a standard deviation of 2.5 hours. Using a significance level of 0.01, can you conclude that your employees work more than 40 hours per week?
Click here to see answer by stanbon(26259) |
Question 132773: In an article in the Journal of Management, Morris, Avila and Allen studied innovation by surveying firms to find the number of new products introduced by the firms. A random sample of 100 California based firms are selected. Each firm is asked to report the number of new products introduced last year. The survey found that on average these firms introduced 5.68 products with a standard deviation of 8.70. Compute a 98% confidence interval for the new products introduced last year.
Click here to see answer by stanbon(26259) |
Question 132473: Suppose that the weights of 10-week old kittens follow a normal distribution, with a mean value of 25 ounces and a standard deviation of 4 ounces. If a kitten’s weight is in the bottom 10% of the distribution of weights, then it is said to be undernourished. What is the cutoff weight for an undernourished kitten?
Click here to see answer by scott8148(3382)  |
Question 132843: Using Feb. Inflow as the dependent variable and Jan. Inflow as the dependent variable.
What is the equation of the regression line?
What is the vaue of the coeifficent of determination.
What is the value of the linear correlation coeefficent. : Year January Inflow February Inflow
1976 2.89 2.45
1977 3.57 2.57
1978 4.18 3.17
1979 4.71 3.93
1980 4.12 2.93
Using Feb. Inflow as the dependent variable and Jan. Inflow as the independent variable.
What is the equation of the regression line?
What is the vaue of the coeifficent of determination.
What is the value of the linear correlation coeefficent.
Click here to see answer by stanbon(26259) |
Question 132824: Which of the following is true of the relationship between the high temperature and the number of hours of daylight in a day in North Carolina?
Answer Choices:
A) positive correlation
B) negative correlation
C) no correlation
D) not enough information
Click here to see answer by stanbon(26259) |
Question 132767: 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 are processed on the same day, would this prove that they are exceeding their goal, using alpha.025?
Click here to see answer by stanbon(26259) |
Question 132766: 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 grater than 10?
Use Excell to find the right-tail p-value.
Click here to see answer by stanbon(26259) |
Question 132525: 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 α = .025?
Click here to see answer by stanbon(26259) |
Question 132475: Suppose that 78% of all Americans support a proposed law to require a police permit before someone is allowed to buy a gun. If a simple random sample of 45 Americans is to be taken, and each person is asked if they support the proposed law, and the sample proportion who do favor such a law is calculated:
a.Specify the sampling distribution of the sample proportion.
b.What is the probability that the sample proportion exceeds 80%?
Click here to see answer by stanbon(26259) |
Question 132907This 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? This question is from textbook Applied Statistics in Business and Economics
Click here to see answer by stanbon(26259) |
Question 132971: Please help. Found the question but the calculations were not available. Thank you in advance. 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 alpha=.05, is the correctness of the prediction different for the two types of cola drinker? Could you identify your favorite brand in this kind of test? Since it is a 2x2 table, try also a two taled two sample z test for п1= п2 and verify that z2 is the same as your chi-square statistic. Which test do you prefer? Why?
Show how the degrees of freedom are calculated, find the critical value of chi-square, and interpret the p-value. Is the conclusion sensitive to the level of significance chosen?
Correct? Regular Cola Diet Cola Row Total
Yes, got it right 7 7 14
No, got it wrong 12 20 32
Col total-------- 19 27 46
Click here to see answer by stanbon(26259) |
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Older solutions: 1..45, 46..90, 91..135, 136..180, 181..225, 226..270, 271..315, 316..360, 361..405, 406..450, 451..495, 496..540, 541..585, 586..630, 631..675, 676..720, 721..765, 766..810, 811..855, 856..900, 901..945, 946..990, 991..1035, 1036..1080, 1081..1125, 1126..1170, 1171..1215, 1216..1260, 1261..1305, 1306..1350, 1351..1395, 1396..1440, 1441..1485, 1486..1530, 1531..1575, 1576..1620, 1621..1665, 1666..1710, 1711..1755, 1756..1800, 1801..1845, 1846..1890, 1891..1935, 1936..1980, 1981..2025, 2026..2070, 2071..2115, 2116..2160, 2161..2205, 2206..2250, 2251..2295, 2296..2340, 2341..2385, 2386..2430, 2431..2475, 2476..2520, 2521..2565, 2566..2610, 2611..2655, 2656..2700, 2701..2745, 2746..2790, 2791..2835, 2836..2880, 2881..2925, 2926..2970, 2971..3015, 3016..3060, 3061..3105, 3106..3150, 3151..3195, 3196..3240, 3241..3285, 3286..3330, 3331..3375, 3376..3420, 3421..3465, 3466..3510, 3511..3555, 3556..3600, 3601..3645, 3646..3690, 3691..3735, 3736..3780, 3781..3825, 3826..3870, 3871..3915, 3916..3960, 3961..4005, 4006..4050, 4051..4095, 4096..4140, 4141..4185, 4186..4230, 4231..4275, 4276..4320, 4321..4365, 4366..4410, 4411..4455, 4456..4500, 4501..4545, 4546..4590, 4591..4635, 4636..4680, 4681..4725, 4726..4770, 4771..4815, 4816..4860
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