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Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 134014: 16 college graduates, of whom 5 are men, have applied for six vacancies in a company. The Company has decided to hire 2 men. If the positions all have different job descrptions, how many ways are there in which the company can make 6 offers of this type?
I know I need to use the equation nCr or nPr, but I really don't understand them. Could you help explain please?! Thanks!
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Question 133742: 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?
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Question 133741: I am not even sure where to start with this problem. Any assistance would be helpful. Thank you!
A survey of 12 people at a bookstore showed that five had purchased a hardcover book. If seven people are selected at random, what is the probability that four of them had purchased a hardcover book?
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Question 133739: I am having a hard time with this one. Can someone please help me??
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.
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Question 133641This question is from textbook Statistics
: I want to see if I did this problem right:
The average afe of CEO's is 56. Assume the cariable is normally distrubited. If the standard deviation is 4 years, find the probability that the age of a randomly selected CEO will be in the following range:
Between 53 and 59 years old.
This is how I did it:
53-56/4 = -.75 then I looked at my chart and found that the average was .2580
59-56/4 = .75 then I looked at the chart and found the average was .2580
then I added the 2 averages together: .2580 + .2580 = .516 = 51.6%This question is from textbook Statistics
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Question 133581: Use the five-step hypothesis testing procedure to solve the following?
As part of a study of corporate employees, the Director of Human Resources for PNC, Inc. wants to compare the distance traveled to work by employees at their office in downtown Cincinnati with the distance for those in downtown Pittsburg. A sample of 35 Cincinnati employees showed they travel a mean of 370 miles per month, with a standard deviation of 30 miles per month. A sample of 40 Pittsburgh employees showed they travel a mean of 380 miles per month, with a standard deviation of 26 miles per month.
At the .05 significance level, is there a difference in the mean number of miles traveled per month between Cincinnati and Pittsburgh employees?
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Question 133521: In the following regression, X = total assets ($ billions), Y = total revenue ($ billions), and n = 64large banks. (a) Write the fitted regression equation. (b) State the degrees of freedom for a twotailedtest 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.
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Question 133491: Gestation Period Mean Birth Weight Standard Deviation
Under 28 weeks 1.88 lb 1.19 lb
28 to 31 weeks 4.07 lb 1.87 lb
32 to 35 weeks 5.73 lb 1.48 lb
36 weeks 6.46 lb 1.20 lb
37 to 39 weeks 7.33 lb 1.09 lb
40 weeks 7.72 lb 1.05 lb
41 weeks 7.83 lb 1.08 lb
42 weeks and over 7.65 lb 1.12 lb
There are 5 exercises
Question 1) The distributions of birth weights for three gestation periods are shown. Match the curves with the gestation periods. Explain your reasoning. (I photographed the curves and they are attached.)
Question 2) What percent of the babies born with each gestation period have a low birth weight (under 5.5 pounds)? Explain your reasoning.
(a) Under 28 weeks (b) 32 to 35 weeks (c) 37 to 39 weeks (d) 42 weeks and over.
Question 3) Describe the weights of the top 10% of the babies born with each gestation period. Explain your reasoning.
(a) 37 to 39 weeks (b) 42 weeks and over
Question 4) For each gestation period, what is the probability that a baby will weigh between 6 & 9 pounds at birth?
(a) 32 to 35 weeks (b) 37 to 39 weeks (c) 42 weeks and over
Question 5) A birth weight of less than 3.3 pounds is classified by the NCHS as a "very low birth weight." What is the probability that a baby has a very low birth weight for each gestation period?
(a) Under 28 weeks (b) 32 to 35 weeks (c) 37 to 39 weeks
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Question 132527: Question 11.24 from Chapter 11 Doane−Seward: 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
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
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Question 132428: Please help. 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?
: Please help. 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 135011: Hi, I was asked to develop a numerical and verbal hypothesis statement and I have but cannot work it. Can someone help me? Here is the hypothesis statement.
1. as part of a study of blue collard citizens, the Director of Human Resources for Whitner Autoplex Car Sales wants to compare the amount of older blue collard citizens purchasing expensive vehicles from Whitner Autoplex, verses those younger in age, purchasing inexpensive vehicles.
A sample of 17 citizens over the age of 50 purchased expensive vehicles, with the mean being 35.925 and with the standard deviation of 80 vehicles sold per month. A sample of 64 citizens under the age of 50 purchased inexpensive vehicles, with the mean being 15.546 and the standard deviation of 70 vehicles sold per month.
At the .05 significance level, is there a difference in the mean number of older citizens, verses the younger citizens, purchasing vehicles at a high rate? The company will use the five-step hypothesis procedure to show the general manager the outcome of sales.
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Question 135009: The x and the y variable in the table below are correlated. Determine the ‘R’ value, and then determine the regression equation.
x y
16.66 28.34
20.70 37.38
24.33 45.52
21.27 39.70
20.01 39.72
27.44 55.54
16.84 30.40
22.27 38.26
14.20 25.68
17.74 33.51
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Question 135008: 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 before after
Homer 19 12
Bart 6 18
Lisa 9 12
Marge 5 7
Maggie 9 14
Ned 8 17
Milhouse 11 9
Willie 11 17
Stu 11 12
Gill 7 7
Run a statistical hypothesis test and determine if the seminar significantly improved sales figures for the company.
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Question 135071: Systems of Linear Equations
The probability that San Francisco plays in the next Superbowl is nine times the probability that they do not play in the next superbowl. The probability 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?
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Question 135217: A coin was flipped 60 times and came up heads 38 times. (a) at the .10 level of significance, is the coin biased toward heards? Show your decision rule and calculations. (b) Calculate a p-value and interpret it.
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Question 135248: Thank you for all your help with this course. But my problem for this week that I am stuck on is:
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. At alpha = .05, is the correctness of the prediction different for the two types of cola drinkers? Could you identify your favor brand in this kind of test? Since it is a 2 x 2 table, try also a two-tailed two-sample z tet for pi1=p12 and verify z squared is the same as your chi-square statistic. Which test do you prefer? Why?
Corect? 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
I saw this problem posted but could not find the answer. Thank you Thank you! You guys are wonderful!
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Question 135273: The probability is 1 in 4,000,000 that a single auto trip in the United States will result in a
fatality. Over a lifetime, an average U.S. driver takes 50,000 trips. (a) What is the probability of
a fatal accident over a lifetime? Explain your reasoning carefully. Hint: Assume independent
events. Why might the assumption of independence be violated? (b) Why might a driver be
tempted not to use a seat belt “just on this trip”?
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Question 135272: 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.
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Question 135301This question is from textbook Statistics
: A random sample of 76 four-year-olds attending day care centers showed that the yearly tuition averaged $3648. The standard deviation of the sample was $630 and the sample size was 50. Find the 90% confidence interval of the true mean. This question is from textbook Statistics
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Question 135295: The x and the y variable in the table below are correlated. Determine the ‘R’ value, and then determine the regression equation.
x----------y
16.66-----28.34
20.70-----37.38
24.33-----45.52
21.27-----39.70
20.01-----39.72
27.44-----55.54
16.84-----30.40
22.27-----38.26
14.20-----25.68
17.74-----33.51
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Question 135312: Hello, Can you help me with this one?
1. You are working with a piece of manufacturing machinery that fills pouches; the pouch weight is supposed to be 8.8 ounces after being filled; you have been asked to see if the mean weight is different from 8.8 ounces … at the 0.05 level of significance.
You have a sample of 14 filled pouches with the following weights:
12 , 6 , 11 , 12 , 5 , 0 , 2 , 7 , 8 , 7 , 6 , 3 , 12 , 12
Use the 5 step hypothesis testing procedure … to determine your conclusion.
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Question 135293: 5.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-------before--------after
Homer-----------19-----------12
Bart------------6------------18
Lisa------------9------------12
Marge-----------5------------7
Maggie----------9------------14
Ned-------------8------------17
Milhouse-------11------------9
Willie---------11------------17
Stu------------11------------12
Gill-----------7-------------7
Run a statistical hypothesis test and determine if the seminar significantly improved sales figures for the company.
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Question 135350: 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?
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Question 135349: 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.
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Question 135343: A company that sells mail order systems has been planning inventory and staffing based on an assumption that the mean of their weekly sales is 180. The weekly sales are normally distributed. The company selects 10 weeks at random from the past year and obtains the data shown below.
Weekly sales:
179 172 170 179 194
189 176 198 193 178
Set up the hypothesis test to test weather the sample mean is different from 185
At the 0.05 significance, what can you conclude about the company's assumption?
Treat as a large sample.
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Question 135333: 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 2081 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 hypotheses. b) Obtain a test statistic and p-value. Interprestthe r resultts at a=.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?
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Question 135377: A vending machine company that dispenses coffee into cups must fill the cups with 7.8oz of liquid. Before selling the vending machine to a college or business, the company tests the machine to be sure it is dispensing an average amount of 7.8oz of coffee. A sample of 6 amounts is shown below. The amount of coffee is assumed to be normally distributed with a standard deviation of 0.10 oz. At the .10 level of significance, does the machine dispense as expected?
Treat as a small sample.
7.81 7.77 7.89 7.83 7.75 7.79
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Question 135397: Here is another one I need help with. Thanks in Advance.
1. If I am surveying the constituents for my favorite candidate ... and I wish to be 95% confident of the estimate I develop for the proportion of the constituents that favor my candidate and i want the error to be within 2% (0.02) of the actual population proportion
>> how many folks do there need to be in my sample ??
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Question 135396: Can someone tell me what this is about?
you are conducting a one tailed, right tail test using the z-test for means;
>> the level of significance is 0.025; question: what is the critical z-value???
>> the calculated z-value is 2.33; question: what is the p-value??
>> finally -- based on the above .. do we accept or reject the null hypothesis?? why or why not??
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Question 135423: 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
What is the arithmetic mean selling price?
What is the median selling price?
What is the modal selling price?
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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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