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Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 138136: Daily output of Marathon's refinery is normally distributed with a mean of 232000 barrels of crude oil per day with a standard deviation of 7000 barrels.
What is the probability of producting at least 232000 barrels?
Between 232000 and 239000 barrels?
Less than 239000 barrels?
Less than 245000 barrels?
More than 225000 barrels?
Click here to see answer by stanbon(26259)   |
Question 138211: I need assitance on this problem...
Answer the following questions, inserting values from the ANOVA table below.
Analysis of Variance
Source DF Sum of Squares Mean Square F Ration Prob > F
Treatment 2 100.5571 50.2786 1.7222 0.1847
Error 87 2539.9445 29.1948
C.Total 89 2640.5017
A. What is the Sum of Squares of Treatment?
B. What is the Total Sum of Squares?
C. What is the Mean Square Error (MSE) ?
D. What is the Test Statistic?
E. What is the P-value?
F. How many treatments (groupings) are being compared?
G. How many total observations are in this analysis?
H. What is the null hypothesis tested here?
Click here to see answer by stanbon(26259) |
Question 138295: I need help fast. Thank you.
A certain broakerae huse wants to estimate the mean daily return on a certain stock. A random sample of 17 days yields the following percentateS:
-1.2, -1.84, -2.93, -1.39,, 0.22, -1.64, -1.56, 1.31, 2.77, 2.69, 2.65, 2.98, -0.56, 2,8, -099, 0.39 and 0,14
If we assume that the return are normally distirbued find a 95%confidendce interval for the mean daily return on this stock.
What is the lower limit on the confireence interval
What is the upper limit of the confidence interval.
Click here to see answer by stanbon(26259) |
Question 138296: Confidence interval for the population mean: Use of the t distribution
A toy manufacturer wants to see how long, on average, a new toy captures children's attention. He tests 20 children selected at random and finds that their mean attention span is 31 minutes with a standard deviation of 6 minutes. If we assume that attention spans are normally distributed, find a 90 confidence interval for the mean attention span of children playing with this new toy. Then complete the table below.
Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place.
(If necessary, consult a list of formulas.)
What is the lower limit of the confidence interval
What is the higher limit of the confience interval
Click here to see answer by stanbon(26259) |
Question 137968: A researcher collected sample data for 11women ages 18 to 24 The sample had a mean serum cholesterol level (measured in mg/100 mL) of 189.9 with a standard deviation of 8.8. Assuming that serum cholesterol levels for women ages 18 to 24 are normally distributed, find a 95 confidence interval for the mean serum cholesterol level of all women in this age group. Then complete the table below.
Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place.
(If necessary, consult a list of formulas
Click here to see answer by stanbon(26259) |
Question 138368: Suppose the average watermelon contains 144.0 brown seeds. Farmer Brown just picked 25 ripe melons from the south side of his big garden and found that the average was 141.0 seeds and the standard deviation was 2.4 seeds. The same test statistic was obtained from another sample of 36 melons picked from the north side of the garden, but this time the standard deviation was 3.6 seeds. What was the average number of seeds in each watermelon picked from the north side?
a. 140.25
b. 140.40
c. 140.54
d. 141.75
Click here to see answer by stanbon(26259) |
Question 138366: Two samples of shelled corn were taken from a bin and the weight of each kernel was measured and compared to the mean from last year’s entire bin. The test statistic from the first sample was 1.8, the test statistic from the second sample was 2.5, and the research team was astonished to learn that the mean and standard deviation were identical for both samples. If the first sample was composed of 16 kernels, how many kernels were weighed on the second occasion?
a. 8
b. 12
c. 22
d. 31
Click here to see answer by stanbon(26259) |
Question 138308This question is from textbook fundamentals of maths
: good morning. my brain is going blank on my problems, can you help me on this one please?a case of soda pop contains six bottles of root beer, six bottles of orange soda, seven bottles of cola, and five bottles of ginger ale.
Find the probability that (a)one bottle is orange soda and two bottles are root beer. thanks.This question is from textbook fundamentals of maths
Click here to see answer by stanbon(26259) |
Question 138432: 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 the probability that (a) both will fail? (b) Neither will fail? (c) One or the other will fail? Show all steps carefully. Any help is much appreciated.
Thank you,
Sean
Click here to see answer by stanbon(26259) |
Question 138544: Help please....
Below are 3 groupings of data. Run an Analysis of Variance on these, and conclude if there is a statistical difference between the 3 groups.
A 13, 16, 14, 16
B 10, 12 , 11, 12
C 14, 14, 15, 14
Click here to see answer by stanbon(26259) |
Question 138548: A sample of 25 households in Prolific City revealed a mean of 7.5 residing members and a standard deviation of 3. If the mean household size for the nation is 4.2, what is the value of the test statistic?
a. 27.5
b. 5.5
c. 1.1
d. 0.55
Click here to see answer by stanbon(26259) |
Question 138546: The weekly sales (in thousands of dollars) the week before and the week after a new Internet sales location is installed are given in the following table for 8 different businesses.
Sales Before Sales After
27 ------------ 32
35 ------------ 36
22 ------------ 23
13 ------------ 12
45 ------------ 48
55 ------------ 57
60 ------------ 58
18 ------------ 30
The alternative hypothesis is HA: d > 0, where d = sales after – sales before. For level of significance 0.10, what is the critical value and the value of the test statistic?
a. 1.645 and 1.70
b. 1.70 and 1.645
c. 1.70 and 1.895
d. 1.895 and 1.70
Click here to see answer by stanbon(26259) |
Question 138586: Statistical software is commonly used for problem solving in the workplace. It is useful to look at a computer generated output to understand the format of the output, how the computerized solution treats an ANOVA table, and so on. The ANOVA table is somewhat standardized among various software packages. Formulate the null and alternate hypothesis and decide whether or not to reject it from the ANOVA table data provided below.
Group 1
5
7
4
5
4
6
8
5
6
7
Group 2
6
7
7
5
6
7
8
6
8
6
Group 3
7
8
9
8
9
9
10
11
10
9
One factor ANOVA
Mean n Std. Dev
7.1 5.7 10 1.34 Group 1
7.1 6.6 10 0.97 Group 2
7.1 9.0 10 1.15 Group 3
7.1 30 1.81 Total
ANOVA table
Source SS df MS F p-value
Treatment 58.20 2 29.100 21.53 2.57E-06
Error 36.50 27 1.352
Total 94.70 29
Post hoc analysis
Tukey simultaneous comparison t-values (d.f. = 27)
Group 1 Group 2 Group 3
5.7 6.6 9.0
Group 1 5.7
Group 2 6.6 1.73
Group 3 9.0 6.35 4.62
critical values for experimentwise error rate:
0.05 2.49
0.01 3.18
p-values for pairwise t-tests
Group 1 Group 2 Group 3
5.7 6.6 9.0
Group 1 5.7
Group 2 6.6 .0949
Group 3 9.0 8.54E-07 .0001
Click here to see answer by stanbon(26259) |
Question 138547: Sherry Weinstein, a buyer, has decided that she will spend an extra $7 per shirt for the next 10,000 T-shirts she buys for her chain of stores only if the vendor of the more expensive shirt can show conclusive evidence that its shirt can withstand at least 20 more times in the wash without fading. The vendor elected to set 1 as the mean number of washes without fading for the more expensive shirt. An appropriate null hypothesis for the vendor to test is:
a. H0: u1 – u2<= 20.
b. H0: u1 – u2 < 20.
c. H0: u1 – u2 > 20.
d. H0: u1 – u2<= 0.
Click here to see answer by stanbon(26259) |
Question 138528: In a bumper test, three types of autos were delibertely 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 showned below. Research question? Are the mean crash damages the same for these three vehicles? crash 1
Goliath 1,600, 760, 880, 1,950, 1,220
Vermint 1,290, 1,400, 1,390, 1,850, 950
Weasel 1,090, 2,100, 1,830, 1,250, 1,920
Click here to see answer by stanbon(26259) |
Question 138510: The mean science achievement score of a group of Grade 8 students is 78 and s of 10. Granting that the scores of these students are normally distributed, how many would you expect to score less than 85? If the number of students who took the test is 200, how many would that be? How many students would score more than 85?
Click here to see answer by stanbon(26259) |
Question 138607: To Stanbon,
Using the first problem you solved on z-score please check this problem I tried to solve:
The mean weight of 545 women is 99lbs. and s is 5, Assuming that the wts. of women are normally distributed, how many would you expect to weigh less than 105?
Z= 105-99/5
z=1.2
from table: Z score = .3848 or 38.48% will weigh more than 105 that is 210 women
computing for women who will weigh less than 105:
100-38.48 = 61.52%
545x.6152 = 335 women who will weigh less 105 lbs.
Thanks again.
Click here to see answer by stanbon(26259) |
Question 138618: 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 four accidents. At a=.01, did the yellow fire trucks have a significantly lower accident rate? (a)state the hypothesis, (b) state the decision rule and sketch it. (c)Find the sample porportions and z test statistics. (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 normanility 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 138655: If 20 students register for a Sociology class and 35 students register for Psychology, and 15 students register for both classes, if one student is selected at random, what is the probability that student only registered for Sociology or Psychology?
Click here to see answer by Edwin McCravy(2920) |
Question 138677: Hello, need some help w/these few. Thanks again, you are awesome!
T F 1. An estimate of the population mean based on a large sample is less reliable than an estimate made using a small sample.
T F 2. The standard error of the mean will vary according to the size of the sample. As the sample size gets larger, the variability of the sample means gets smaller.
T F 3. One misconception about the number to sample is that a larger sample of voters must be selected from a heavily populated state, such as New York, than from a small state such as Nevada.
T F 4. If nonprobability sampling methods are used, the results may be biased.
T F 5. The Central Limit Theorem states that if all samples of a particular size are selected from any population, the sampling distribution of the sample means is approximately a normal distribution.
T F 6. If the size of a sample equals the size of the population, we would not expect any error in estimating the population parameter.
Click here to see answer by stanbon(26259) |
Question 138658: An insurance company charges $200 for a life insurance premium for people under the age of 18 that pays out $15,000. The probability that someone dies before their 18th birthday is 0.0025. What is the expected payout by the insurance company? How much of that profit/loss does the company make?
Click here to see answer by stanbon(26259) |
Question 138647: A regress analysis between sales (Y in $1000) and advertisting (X in dollars) resulted in the following equation
^Y = 30,000 + 4 X
The above equation implies that an
A) increase of $4 in advertising is associated with an increase of $4,000 in sales.
B) increase of $1 in advertising is associated with an increase of $4 in sales.
C) increase of $1 in advertising is associated with an increase of $34,000 in sales.
D) increase of $1 in advertising is associated with an increase of $4,000 in sales.
Click here to see answer by stanbon(26259) |
Question 138699: Please help with this problem. Don't know which text the intructor got it from. Thank you!!
A sample of 36 observations is selected from a normal population. The sample mean is 21, and the sample standard deviation is 5. Conduct the following test of hypothesis using the .05 significance level.
H0: µ ≥ 20
H1: µ < 20
Answer the Questions: (a) Is this a one or two tailed test? (b) What is the decision rule? (c) What is the value of the test statistic? (d) What is your decision regarding H0? (e) What is the p-value? Interpret it.
Click here to see answer by stanbon(26259) |
Question 138728: Sixty-four students in an introductory college economics class were asked how many credits they had earned in college, and how certain there were about their choice of major. Research question: At a=.01, is the degree of certainty independent or credits earned? Row 1 credits earned --Row 2 very uncertain --Row 3 somewhat certain --Row 4 very certain -- Row 5 Row total
Credits earned very uncertain somewhat certain very certain Row total
0-9 12 8 3 23
10-59 8 4 10 22
60 or more 1 7 11 19
Col Total 21 19 24 64
Click here to see answer by stanbon(26259) |
Question 136507: I am having problems trying to figure out can you help thanks.
In a bumper test, three types of autos were deliberately crashed into a barrier at 5 mph, and the resulting damage (in dollars) was estimated. Five test vehicles of each type were crashed, with the results shown below. Research question: Are the mean crash damages the same for these three vehicles.
Crash Damage ($)
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
Click here to see answer by melissa182(1) |
Question 138706: Stan, will you please explain how you got the answers below. Thank you very much
The ANOVA table is somewhat standardized among various software packages. Formulate the null and alternate hypothesis and decide whether or not to reject it from the ANOVA table data provided below.
------------------------------------------
One factor ANOVA
Mean n Std. Dev
7.1 5.7 10 1.34 Group 1
7.1 6.6 10 0.97 Group 2
7.1 9.0 10 1.15 Group 3
7.1 30 1.81 Total
ANOVA table
Source.. SS df MS F p-value
Treatment 58.20 2 29.100 21.53 ...2.57E-06
Error ........36.50 27 1.352
Total ........94.70 29
Post hoc analysis
Tukey simultaneous comparison t-values (d.f. = 27)
Group 1 Group 2 Group 3
5.7 6.6 9.0
Group 1 ........5.7
Group 2 ........6.6 1.73
Group 3 ........9.0 6.35 4.62
critical values for experimentwise error rate:
0.05 2.49
0.01 3.18
p-values for pairwise t-tests
Group 1 Group 2 Group 3
5.7 6.6 9.0
Group 1 ........5.7
Group 2 ........6.6 .0949
Group 3 ........9.0 8.54E-07 .0001
---------------------------------------------------
Ho: The means of the three Groups were all equal
Ha: At least one of the means was different.
Since p-value = 0.00000257, Reject Ho.
Conclusion: At least one of the mean values is different.
===============================
Cheers,
Stan H.
Click here to see answer by stanbon(26259) |
Question 138779This question is from textbook APPLIED STATISTICS IN BUSINESS AND ECONOMICS
: 13.32 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).
Interpret these results.
Variable Coefficient t p
Intercept −3,816,521 −29.4 .000
Year 1,948 29.8 .000
YearHire −826 −5.5 .000
Race −2,093 −4.3 .000
Rank −6,438 −22.3 .000
R2 = 0.811 R2
adj = 0.809 s = 3,318This question is from textbook APPLIED STATISTICS IN BUSINESS AND ECONOMICS
Click here to see answer by stanbon(26259) |
Question 138790: 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
Applying ANOVA and Nonparametric Tests Simulation
Click here to see answer by stanbon(26259) |
Question 138793: 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.
Digit Frequency
0 33
1 17
2 25
3 30
4 31
5 28
6 24
7 25
8 32
9 25
Total 270
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?
Click here to see answer by stanbon(26259) |
Question 138805: 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 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 (see Chapter 10) and verify that z2 is the same as your chi-square statistic.Which
test do you prefer? Why?
Below is the table:
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) |
Question 138787This question is from textbook
: 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. (Data are from a project by MBA student Henry Scussel.)This question is from textbook
Click here to see answer by stanbon(26259) |
Question 138698: Please help with this problem. Don't know which text the instructor got it from. Thank you!
The following sample observations were randomly selected
X: 5 3 6 3 4 4 6 8
Y: 13 15 7 12 13 11 9 5
Determine the coefficient of correlation and the coefficient of determination. Interpret.
Click here to see answer by stanbon(26259) |
Question 138778This question is from textbook APPLIED STATISTICS IN BUSINESS AND ECONOMICS
: 13.30 A researcher used stepwise regression to create regression models to predict BirthRate (births per
1,000) using five predictors: LifeExp (life expectancy in years), InfMort (infant mortality rate),
Density (population density per square kilometer), GDPCap (Gross Domestic Product per capita),
and Literate (literacy percent). Interpret these results.
Regression Analysis—Stepwise Selection (best model of each size)
153 observations
BirthRate is the dependent variable
p-values for the coefficients
Nvar LifeExp InfMort Density GDPCap Literate s Adj R2 R2
1 .0000 6.318 .722 .724
2 .0000 .0000 5.334 .802 .805
3 .0000 .0242 .0000 5.261 .807 .811
4 .5764 .0000 .0311 .0000 5.273 .806 .812
5 .5937 .0000 .6289 .0440 .0000 5.287 .805 .812This question is from textbook APPLIED STATISTICS IN BUSINESS AND ECONOMICS
Click here to see answer by stanbon(26259) |
Question 138784: Please help with this problem. No ISBN available to provide. Thank you!!!!
. The following sample observations were randomly selected
X: 5 3 6 3 4 4 6 8
Y: 13 15 7 12 13 11 9 5
Determine the coefficient of correlation and the coefficient of determination. Interpret.
Click here to see answer by stanbon(26259) |
Question 138776This 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. (f) In your own words, describe the fit of this regression.
R2 0.202
Std. Error 6.816
n 35
ANOVA table
Source SS df MS F p-value
Regression 387.6959 1 387.6959 8.35 .0068
Residual 1,533.0614 33 46.4564
Total 1,920.7573 34
Regression output confidence interval
variables coefficients std. error t (df = 33) p-value 95% lower 95% upper
Intercept 30.7963 6.4078 4.806 .0000 17.7595 43.8331
Slope 0.0343 0.0119 2.889 .0068 0.0101 0.0584This question is from textbook APPLIED STATISTICS IN BUSINESS AND ECONOMICS
Click here to see answer by stanbon(26259) |
Question 138864This question is from textbook
: The Rocky Mountain district sales manager of Book Publishing, Inc., a college textbook publishing company, claims that the sales representatives make an average of 45 sales calls per week on professors. Several reps say that this estimate is too low. To investigate, a random sample of 32 sales representatives reveals that the mean number of calls made last week was 46. The standard deviation of the sample is 3.3 calls. Using the .05 significance level, can we conclude that the mean number of calls per salesperson per week is
more than 45?
This question is from textbook
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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