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Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 138919: All possible samples of size n are selected from a population and the mean of each sample is calculated. What is the value of the mean of the sample means?
a. 0Smaller than the population mean
b. 0Larger than the population mean
c. 0Exactly the same as the population mean
d. 0It cannot be determined in advance
e. 0None of the above
Click here to see answer by oscargut(682)   |
Question 138914: In order to use the test statistic for the difference between two sample means both samples must have a population of at least 30 and the samples must be from dependent populations. Is this answer true or false?
Click here to see answer by stanbon(26259)  |
Question 138949: 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.
Accident Rate for Dallas Fire Trucks
Statistic Red Fire Trucks Yellow Fire Trucks
Number of accidents x1 = 20 accidents x2 = 4 accidents
Number of fire runs n1 = 153,348 runs n2 = 135,035 runs
Click here to see answer by stanbon(26259) |
Question 138984: A researcher believes that the average production in manufacturing has increased by 200 units. The hypothesis statement for this situation is:
a. 0H0: = 200
HA: 200
b. 0H0: 200
HA: < 200
c. 0H0: < 200
HA: > 200
d. 0None of the above
Click here to see answer by stanbon(26259) |
Question 138983: The following hypotheses is an example of:
HO: p ≤ .40
HA: p > .40
a. 0A one-tail test for means
b. 0A two-tail test for means
c. 0A one-tail test for proportions
d. 0A two-tail test for proportions
e. 0None of the above
Click here to see answer by stanbon(26259) |
Question 138998: An expert witness in a case of alleged racial discrimination in a state university school of nursing
introduced a regression of the determinants 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).
Click here to see answer by stanbon(26259) |
Question 138977: A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on a very accurate scale. The results in grams were
3.087
3.131
3.241
3.241
3.270
3.353
3.400
3.400
3.437
3.477
(a) Construct a 90 percent confidence interval for the true mean weight.
(b) What sample size would be necessary to estimate the true weight with an error of + 0.03 grams with 90 percent confidence?
(c) Discuss the factors which might cause variation in the weight of Tootsie Rolls during manufacture
Click here to see answer by stanbon(26259) |
Question 138921: The following hypotheses is an example of:
HO: m ≠ .40
HA: m = .40
a. 0A one-tail test for means
b. 0A two-tail test for means
c. 0A one-tail test for proportions
d. 0A two-tail test for proportions
e. 0None of the above
Click here to see answer by stanbon(26259) |
Question 138920: The following hypotheses is an example of:
HO: p ≤ .40
HA: p > .40
a. 0A one-tail test for means
b. 0A two-tail test for means
c. 0A one-tail test for proportions
d. 0A two-tail test for proportions
e. 0None of the above
Click here to see answer by stanbon(26259) |
Question 139014: An independent consumer group published its finding that the lifetimes of electric bulbs manufactured by BIG Corporation are approximately normally distributed with a mean of days and a standard deviation of . BIG Corporation claims that the standard deviation of its electric bulbs is less than . Suppose that we want to carry out a hypothesis test to see if BIG Corporation's claim is correct. State the null hypothesis and the alternative hypothesis that we would use for this test.
Click here to see answer by stanbon(26259) |
Question 139005: A researcher believes that the average production in manufacturing has increased by 200 units. The hypothesis statement for this situation is:
a. H0: u = 200
HA: u not equal to 200
b. H0: u greater then equal to 200
HA: u < 200
c. H0: u less then or equal to 200
HA: u > 200
d. None of the above
Click here to see answer by stanbon(26259) |
Question 139000: every 15 min. the fast train arrives & waits 4 min. Then 4 min. after the fast train leaves, the local train arrives & waits 3 min. If you arrive at the station at a random time during the rush period, find the probability that the fast train will be waiting and find the probability that no train will be there.
Click here to see answer by stanbon(26259) |
Question 139000: every 15 min. the fast train arrives & waits 4 min. Then 4 min. after the fast train leaves, the local train arrives & waits 3 min. If you arrive at the station at a random time during the rush period, find the probability that the fast train will be waiting and find the probability that no train will be there.
Click here to see answer by solver91311(5072)  |
Question 138845: help please...
Analysis of Variance
Source DF Sum of Squares Mean Square F Ratio Prob >F
Treatment 2 100.5571 50.2786 1.7222 0.1847
Error 87 2539.9445 29.1948
C. Total 89 2640.5017
A. How many total observations are in this analysis?
B. What is the null hypothesis tested here?
Click here to see answer by stanbon(26259) |
Question 139052: Stanbon here are the other two that I needed to repost. I know it gets late there as I'm in another country, thanks for all of your help, your the best.
1. In Utica, Michigan, 205 of 226 school buses passed the annual safety inspection. In Detroit, Michigan, only 151 of 296 buses passed the inspection.
(a) State the hypotheses for a right-tailed test.
(b) Obtain a test statistic and p-value. (c) Is normality assured? (d) If significant, is the difference also large enough to be important?
2. Prof. Green’s multiple-choice exam had 50 questions with the distribution of correct answers shown below. Research question: At α = .05, can you reject the hypothesis that Green’s exam answers came from a uniform population
Correct Answer Frequency
A 8
B 8
C 9
D 11
E 14
Total 50
Click here to see answer by stanbon(26259) |
Question 139039: 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 _____ 1290 ______ 1090
760 _____ 1400 ______ 2100
880 _____ 1390 ______ 1830
1,950 _____ 1850 ______ 1250
1,220 _____ 950 ______ 1920
Click here to see answer by stanbon(26259) |
Question 139058: a.) What are the three lessons you learned relative ANOVA and nonparametric tests?
b.) As a result of using this simulation, what concepts and analytic tools will you be able to use in your workplace (i.e., how do you expect to apply what you learned)?
Based on your experience, what additional information would you recommend to the key decision maker in the simulation to solve the challenge given?
Click here to see answer by stanbon(26259) |
Question 139125: A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on
a very accurate scale. The results in grams were
3.087 3.131 3.241 3.241 3.270 3.353 3.400 3.411 3.437 3.477
(a) Construct a 90 percent confidence interval for the true mean weight. (b) What sample size
would be necessary to estimate the true weight with an error of ± 0.03 grams with 90 percent confidence?
(c) Discuss the factors which might cause variation in the weight of Tootsie Rolls during
manufacture.
Click here to see answer by stanbon(26259) |
Question 139208: High levels of cockpit noise in an aircraft can damage the hearing of pilots who are exposed to this
hazard for many hours. A Boeing 727 co-pilot collected 61 noise observations using a handheld
sound meter. Noise level is defined as “Low” (under 88 decibels), “Medium” (88 to 91 decibels),
or “High” (92 decibels or more). There are three flight phases (Climb, Cruise, Descent). Research
question: At α = .05, is the cockpit noise level independent of flight phase? (Data are from Capt. Robert E. Hartl, retired.) Noise
Noise Level Climb Cruise Descent Row Total
Low 6 2 6 14
Medium 18 3 8 29
High 1 3 14 18
Col Total 25 8 28 61
Click here to see answer by stanbon(26259) |
Question 139240: The number of admissions for Carolinas Medical Center hospital emergency room over the course of a lunar cycle was 129 patients per 36 days per full moon as compared to 1,315 patients per 330 days per nonfull moon days
Perform a chi-square test on the data. Use the test to prove (or disprove) that hospital emergency room admissions are dependent (or independent) on (of) the full moon lunar phase.
Full moons were defined as three-day periods in the 29.531-day lunar cycle, with the middle day being described in the world almanac as the full moon.
Click here to see answer by stanbon(26259) |
Question 139150: Hi, I need your assistance with this question: Thanks for your help!
15.22 A student team examined parked cars in four different suburban shopping malls. One hundred vehicles were examined in each location. Research question: At α = .05, does vehicle type vary by mall location? (Data are from a project by MBA students Steve Bennett, Alicia Morais, Steve Olson, and Greg Corda.)
Vehicle Type Somerset Oakland Great Lakes Jamestown Row Total
Car 44 49 36 64 193
Minivan 21 15 18 13 67
Full-sized Van 2 3 3 2 10
SUV 19 27 26 12 84
Truck 14 6 17 9 46
Col Total 100 100 100 100 400
Click here to see answer by stanbon(26259) |
Question 139140: A student team examined parked cars in four different suburban shopping malls. One hundred vehicles were examined in each location. Research question: At a=.05, does vehicle type vary by mall location?
Vehicle Type______Somerset____Oakland____Great Lakes______Jamestown______Total
Car________________44__________49__________36_____________64_________193
Minivan_____________21__________15__________18_____________13_________67
Full-sized Van________02__________03__________03_____________02_________10
SUV_______________19__________27__________26_____________12_________84
Truck______________14__________06__________17_____________09_________46
Col Total___________100_________100_________100____________100________400
Click here to see answer by stanbon(26259) |
Question 139310: I need desperate help on this problem....
A manager hopes to improve the sales figures for 10 employees by sending them to a motivational seminar. To test the effectiveness of this seminar, the manager compares the sales figures for each salesperson for the month immediately prior to the seminar and the month immediately following it.
Employee
Homer
Bart
Lisa
Marge
Maggie
Ned
Milhouse
Willie
Stu
Gill
Before
19
6
9
5
9
8
11
11
11
7
After
12
18
12
7
14
17
9
17
12
7
Run a statistical hypothesis test and determine if the seminar significantly improved sales figures for the company.
Click here to see answer by stanbon(26259) |
Question 139126: In 1992, the FAA conducted 86,991 pre-employment drug tests on job applicants who were to be
engaged in safety and security-related jobs, and found that 1,143 were positive. (a) Construct a
95 percent confidence interval for the population proportion of positive drug tests. (b) Why is the
normality assumption not a problem, despite the very small value of p?
Click here to see answer by stanbon(26259) |
Question 139332: Need help with problem.....
The x and the y variable in the table below are correlated. Determine the ‘R’ value, and then determine the regression equation. Also calculate the Sum of Squares Error (SSE).
X
16.66
20.70
24.33
21.27
20.01
27.44
16.84
22.27
14.20
17.74
Y
28.34
37.38
45.52
39.70
39.72
55.54
30.40
38.26
25.68
33.51
Click here to see answer by stanbon(26259) |
Question 139353: having problems figuring this out. help please
A regular ANOVA will be used to compare 3 groups, called A, B, and C. What is the correct null hypothesis for ANOVA?
a.. Ho: μA= μB= μC
b. Ho: μA≠ μB≠ μC
c. Ho: μA<μB<μC
d. Ho: μA=μB or μA=μC
Click here to see answer by stanbon(26259) |
Question 139460: Stan, please explain the characteristics of a Chi-Square Goodness of Fit hypothesis test as well as the Chi-Square test for independence. Please provide an example of using one of these hypothesis test. Please be specifc providing the steps to the hypothesis test in your exmaple.
Click here to see answer by stanbon(26259) |
Question 139471: need help with these problems.
a. What is the F critical value to be used at the 0.05 level of significance with 7 numerator degrees of freedom and 12 denominator degrees of freedom?
b. What is the chi-square critical value with 12 degrees of freedom for a 0.05 probability?
c. What is the exact probability of a value that fits a chi-square distribution with 17 degrees of freedom being higher than 30.995?
d. I have a sample of 13 units and I want to run a hypothesis test comparing the average to a set value. The hypothesis test uses an alpha of 0.05. What critical value would be used to compare the test statistic against?
Click here to see answer by stanbon(26259) |
Question 139505: I need help with this one!
IQ scores have a normal distribution with a mean of 100 and a standard deviation of 15. Out of a student body of 1800 students, how many would you expect expect to have an IQ above 109?
My answer is: 1800 - 100 = 1700 / 15 = 113.3333
Click here to see answer by stanbon(26259) |
Question 139502: A local company wanted to predict the weekly sales based on the weekly newspaper advertising dollars. The model that result is: Å·= 1.1 + 1.7x, where the dependent variable is the amount of sales, in thousands of dollars, realized during the week and the independent variable is the amount spent on newspaper advertising, in hundreds of dollars, during the week. Interpret the meaning of the values “1.1” and “1.7” in the context of the problem.
Click here to see answer by stanbon(26259) |
Question 139426: 1. What is the difference between strong negative and strong positive r? What does the correlation tell you?
2. During the years 1790 to 1820, the correlation between the number of churches built in New England and barrels of Rum imported into the region was a perfect 1.0. What does this tell you – that church building causes rum drinking, that rum drinking causes church building, or something else? If something else, what?
Click here to see answer by stanbon(26259) |
Question 139772: I need help on this problem....thanks
2. For the ANOVA table below, answer each question.
A. How many treatments (groupings) are being compared?
B. How many total observations are in this analysis?
C. What is the hypothesis tested here?
Source DF Sum of Squares Mean Square F Ratio Prob>F
ID 2 49.38620 24.6931 1.4837 0.2415
Error 33 549.20797 16.6427
C. Total 35 598.59417
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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