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Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 135424: 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
What is the experiment?
List one possible event.
What is the probability that a particular driver had exactly two speeding violations?
What concept of probability does this illustrate?
Click here to see answer by stanbon(26259)   |
Question 135443This question is from textbook Statistics
: The proportion of students in private schools is around 11%. A random sample of 450 students from a wide geographic area indicated that 55 attended private schools. Estimate the true proportion of students attending private schools with 95% confidence.
I can't remember how to find the standard deviation..so i'm really confused.This question is from textbook Statistics
Click here to see answer by stanbon(26259) |
Question 135433: In establishing warranties on HDTV sets, the manufacturer wants to set the limits so that few will need repair at manufacturer expense. On the other hand, the warranty period must be long enough to make the purchase attractive to the buyer. For a new HDTV the mean number of months until repairs are needed is 36.84 with a standard deviation of 3.34 months. Where should the warranty limits be set so that only 10 percent of the HDTVs need repairs at the manufacturer's expense?
Click here to see answer by stanbon(26259) |
Question 135274: I saw this question earlier but it wasn't answered and there was no dataset included so I'm posting again.
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---387.6956-----1------387.6959----8.35---.0068
Residual-----1,533.0614---33-----46.4564
Total--------1,920.7573---34
Regression output----------------------------------------confidence interval
variables----coeff-----std.error---t(df = 33)----p-val----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------0.0584
Click here to see answer by stanbon(26259) |
Question 135532: A sample is taken prior to a major Election of likely voters. The null hypothesis is that the votes will be split 50/50. One candidate gets 54% of the support in the sample, and the P-value for this sample is calculated to be 0.12. What is the correct interpretation of the P-value?
A)There is a 95% probability that the true population percentage is 54% plus/minus 12%.
B)The candidate has only a 12% chance of loosing the election.
C)Assuming that the true percentage actually supporting the candidate is 50%, there is a 0.12 probability that a sample will show results of 54% or greater.
D)12% of the votes in the upcoming election are uncertain, the rest can be estimated.
Click here to see answer by stanbon(26259) |
Question 135535: 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 135556: 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?
Click here to see answer by stanbon(26259) |
Question 135573: Which of these variables are discrete and which are continuous random variables?
a. The number of new accounts established by a salesperson in a year.
b. The time between customer arrivals to a bank ATM.
c. The number of customers in Big Nick’s barber shop.
d. The amount of fuel in your car’s gas tank.
e. The number of minorities on a jury.
f. The outside temperature today
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Question 135575: birth weights are normally distributed with the mean of 3570g and a standard deviation of 495g. if a hospital wants to watch carefully the lightest 2% of infants, find the weight that seperates the bottom 2% from others.
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Question 135564: 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?
Click here to see answer by stanbon(26259) |
Question 135562: 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?
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Question 135531: 1. After a sample of numbers is taken from a population, the 95% confidence interval is calculated out at {10.5, 12.0}
What is the correct way to interpret this confidence interval? Choose one.
A)95% of all values in the population are between 10.5 and 12.0
B)There is a 95% probability that the true population parameter is between 10.5 and 12.0.
C)The true population mean has to be between 10.5 and 12.0
D)The mean is between 10.5 and 12.0, and the standard deviation is 95.
Click here to see answer by stanbon(26259) |
Question 135525This question is from textbook Statistics
: A recent study of 100 people in Miame found 27 were obese. Find the 90% confidence interval of the population proportion of individuals living in Miami who are obese.
I think I started the problem correct but i'm not sure where to go from here...
.27-This question is from textbook Statistics
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Question 135432: 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?
Click here to see answer by stanbon(26259) |
Question 135431: 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?
Click here to see answer by stanbon(26259) |
Question 135604This question is from textbook
: A coin was flipped 60 times and came up heads 38 times. (a) At the .10 level of significance, is the
coin biased toward heads? Show your decision rule and calculations. (b) Calculate a p-value and
interpret it.This question is from textbook
Click here to see answer by stanbon(26259) |
Question 135683: I would like to know what the probability of taking three cards from a full deck of cards and having at least one jack,queen or king in the three cards. I have been told that the answer is 12/52 X 12/51 X 12/50 or about 70% and I feel that this is wrong. Please advise how to figure this out. Thank you.
Click here to see answer by stanbon(26259) |
Question 135683: I would like to know what the probability of taking three cards from a full deck of cards and having at least one jack,queen or king in the three cards. I have been told that the answer is 12/52 X 12/51 X 12/50 or about 70% and I feel that this is wrong. Please advise how to figure this out. Thank you.
Click here to see answer by solver91311(5072)  |
Question 135687: I would like to know what the probability of taking three cards from a full deck of cards and having at least one jack,queen or king in the three cards. I have been told that the answer is 12/52 X 12/51 X 12/50 or about 70% and I feel that this is wrong. Please advise how to figure this out. Thank you.
Click here to see answer by solver91311(5072) |
Question 135710: jennifer has 8 blue marbles, 12 orange marbles, & 10 red marbles
What is the probability of picking an orange marble.
Predict the number of times out of 120 Jennifer will pick an orange marble.
Please help to explain so we can show the work.
Click here to see answer by vleith(1977) |
Question 135710: jennifer has 8 blue marbles, 12 orange marbles, & 10 red marbles
What is the probability of picking an orange marble.
Predict the number of times out of 120 Jennifer will pick an orange marble.
Please help to explain so we can show the work.
Click here to see answer by solver91311(5072) |
Question 135763: The following data give the annual production of wheat in lack tons in Faisalabad. Fit a straight line with the help of least squares method and find the trend value for year too.
Year 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975
Pro 3.6 4.3 5.6 6.2 6.6 5.0 6.3 6.5 6.3 6.4
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Question 135744: I'm in an online class so there is no textbook, please help, thanks.
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 sample 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 α = .05, is there a difference
in variances? Show all steps clearly, including an illustration of the decision rule.
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Question 135786: 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 135790: A pizza parlor has a choice of 12 toppings for its pizzas. From these 12toppings, how many different 4-topping pizzas can be ordered? Assume that the order in which the toppings are listed does not matter.
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Question 135910: I need help on this question this is part of a test. Does not show the text book instructor used.
3. An engineer in a widget factory wants to make a change to the process, and to switch to a cheaper supplier of the crucial raw material in the manufacture of widgets (that is, of course, widgeterium). It is important that the weight of the finished widgets not be different from the specified weight of 10 grams. A sample of 40 widgets created on a test run of the new material has an average weight of 10.8 grams, with a standard deviation of 2. Show work
a. Identify the null and alternative hypothesis
b. Calculate the proper test statistic
c. Calculate the proper P-value
d. In plain English, properly interpret the results, using a significance level of 0.05.
Click here to see answer by stanbon(26259) |
Question 135787: A careful count of 13,789 carcasses of bugs killed by “mosquito zappers” used in homes near water showed that only 18 were mosquitoes. (a) Construct a 90 percent confidence interval for the proportion of all zapped bugs that are mosquitoes. (b) Is a confidence interval really helpful in deciding whether the devices fulfill their purpose? Explain
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Question 135937: A coin-operated coffee machine made by BIG Corporation was designed to discharge a mean of eight ounces of coffee per cup. If it dispenses more that that on average, the corporation may lose money, and if it dispenses less, the customers may complain.
BIG Corporation would like to estimate the mean amount of coffee, , dispensed per cup by this machine. BIG will choose a random sample of cup amounts dispensed by this machine and use this sample to estimate . Assuming that the standard deviation of cup amounts dispensed by this machine is 0.42 ounces, what is the minimum sample size needed in order for BIG to be 90% confident that its estimate is within 0.08 ounces of ?
Carry your intermediate computations to at least three decimal places. Write your answer as a whole number (and make sure that it is the minimum whole number that satisfies the requirements).
Click here to see answer by stanbon(26259) |
Question 135935: The lifetime of a certain brand of battery is known to have a standard deviation of 9 hours. Suppose that a random sample of 100 such batteries has a mean lifetime of 45.6 hours. Based on this sample, find a 95% confidence interval for the true mean lifetime of all batteries of this brand. Then complete the table below.
Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place.
What is the lower limit of 95% confindence interval?
What is the upper limit of 95% confindence interval?
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Question 136064: In a class of 30 studnts, there are 17 girls and 13 boys. Five are A students, and three of these students are girls. If a student is chosen at random, what is the probability of choosing a girl and a A student?
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Question 136094: Suppose that a researcher is interested in estimating the mean systolic blood pressure, , of executives of major corporations. He plans to use the blood pressures of a random sample of executives of major corporations to estimate . Assuming that the standard deviation of the population of systolic blood pressures of executives of major corporations is26 mm Hg, what is the minimum sample size needed for the researcher to be 99% confident that his estimate is within 6 mm Hg of ?
Carry your intermediate computations to at least three decimal places. Write your answer as a whole number (and make sure that it is the minimum whole number that satisfies the requirements).
Click here to see answer by stanbon(26259) |
Question 136093: An aptitude test is designed to measure leadership abilities of the test subjects. Suppose that the scores on the test are normally distributed with a mean of 580 and a standard deviation of 125 . The individuals who exceed 780 on this test are considered to be potential leaders. What proportion of the population are considered to be potential leaders? Round your answer to at least four decimal places.
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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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