Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 133066: The probablility 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 US driver takes 50,000 trips. (a) What is the probablilty 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 133130: The number of grams of a certain radioactive substance present at time t is given by the formula A = 100e^-0.002t, where t is the number of years. Find the number of grams that are present at time t = 0 and time t = 300
Thank you for your help
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Question 133227This question is from textbook Applied Statistics in Business and Economics
: In Dallas, some fire trucks were painted yellow (instead of red) to heighten their visibility. During the 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 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 proportions and = 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.
This question is from textbook Applied Statistics in Business and Economics
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Question 133094: In Dallas, some fire trucks were painted yellow (instead of red) to heighten their visibility. During the 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 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 proportions and = 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.
Click here to see answer by stanbon(26259) |
Question 132942This question is from textbook Applied Statistics in Business and Economics
: 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 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 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
No. of accidents X,=20 accidents X2=4 accidents No. of fire runs N,=153,348 runs N2=135,035 runs This question is from textbook Applied Statistics in Business and Economics
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Question 132908This question is from textbook Applied Statistics in Business and Economics
: 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 hypothesis. (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 X,= 20 accidents X2 = 4 accidents
Number of fire runs N1= 153,348 runs N2= 135,035 runs
This question is from textbook Applied Statistics in Business and Economics
Click here to see answer by stanbon(26259) |
Question 132479: 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 a = .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
Click here to see answer by stanbon(26259) |
Question 133093: I couldn't find the solution for the following question, though it shows as answered. Please help.
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?
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Question 133129: If $9,000 is invested for t years at 8% interest compounded continuously, the future value is given by s = 9,000e^0.08t dollars.
a) graph this function for 0 ≤ t ≤ 15
b) use the graph to estimate when the future will be $16,000
Thank you for your help!
Click here to see answer by stanbon(26259) |
Question 133353: An auto repair shop takes an average of 45 minutes to complete a repair job. The owner of the shop has determined the repair time has a standard deviation of 8 minutes. A customer comes into the shop and states that she will return in 35 minutes -- at which time she must have the car ready to drive off. Using the normal probability distribution, what is the probability the car will be repaired in 35 minutes or less?
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Question 133335: The engineer in a widget factory wants to test out a new form of raw materials. So a batch of widgets are made in the old manner as a control group and then a batch are made with the new materials as a comparison. If the widget weight is statistically the same on both sets, the new materials will be used. The weights of the 10 old process widgets and the 10 new process widgets are seen below.
Old New
36.19 36.20
35.80 36.62
36.00 36.03
36.19 36.40
36.18 36.44
36.11 36.02
36.13 36.12
36.48 36.56
35.98 36.05
36.40 36.44
1. Define this situation as either a 2 sample test or a paired test. Why?
2. Calculate a test statistic
3. Calculate a p-value
4. Give an accurate statement as to whether or not the new widget material should be used. Use a significance level of 0.05.
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Question 133400: 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?
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Question 133415: Hi, I'm at a lost and need some help. Could you please help me with chapter 8 problems 8.46 and 8.62 from the chapter exercise section. Also can you please help me with these problems. 1)The score on the entrance test for a well known law school has a mean score of 200 points and a standard deviation of 50 points. At value should the lowest passing score be set if the school wishes only 2.5% of those taking the entrance test to pass? and ....2)A tire manufacturer wishes to investigate the thread life of its tires. A sample of 10 tires driven 50,000 miles revealed a sample mean of 0.32 inches of thread remaining with a standard deviation of 0.09 inches. Construct a 95% confidence interval for the population mean. Would it be reasonable for the manufacturer to conclude that after 50,000 miles the population mean amount of thread remaining is 0.30 inches? I'm really confussed and is in great need of help.
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Question 133389This question is from textbook
: 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?This question is from textbook
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Question 133328: I can't seem to find a right solution for this problem:
If you are dealt an Ace and King of Clubs in Texas Hold'em poker, what is the probability of not hitting any of the nine poker hands. (see this link for poker hands) http://en.wikipedia.org/wiki/Rank_of_hands_(poker)
Please note that since you are dealt two cards there are now only fifty cards in the deck. And this problem does not account for any "Burn" cards, so it is such that you are just flipping over five cards. In other words, do not include burn cards.
I hope that you can answer my question and it probably helps if you know a small amount about Texas Hold'em...
Click here to see answer by stanbon(26259) |
Question 133481: 4. Consider the following contingency table:
Under 20 21-30 31-40
Male 12 12 17
Female 13 16 21
a. If one person is selected at random, what is the probability that person is Female? ______
b. If one person is selected at random, what is the probability that person is either under 20 or over 30? _______
c. If one person is selected at random, what is the probability that person is either male or in the age group 21-30? _____
d. If two people are selected at random, what is the probability they are both female? ______
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Question 133478: A normal distribution with a mean of 55 and a standard deviation of 6 is evaluated to solve a business problem. What is the probability that any value in the population is between 55 and 65? ___________. What is the probability that any value in the population is between 45 and 65? ____________.
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Question 133479: A business owner decides to use a binomial distribution to solve one of his problems. He knows there is a 60 percent probability that he will sell one of his Red Oak floors to any customer who comes into his shop and views the wood. Out of the next 7 people who come into his shop, what is the probability that 3 people will buy a Red Oak floor? ___________ What is the probability that more than four people will buy the Red oak floor? ___________
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Question 133509: Question, please help! On line course, No ISBN provided.
High level of cockpit noise in an aircraft can damage hearing of pilots who are exposed to this hazard for many hours. A Beoing 727 co-pilot collected 61 noise observations using a handled sound meter. Noise level is defined as "low (under 88 decibles), Medium (88 to 91), high (92 or more). There are three flight phases (Climb,Cruise,Descent). At alph=.05, is the cockpit noise level independent of flight phase? State hypothesis, show degrees of freedom, find critical value of chisquare, and interpret p=value.
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
Thank you!
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Question 133505: Please help, I don't have an ISBN number because its an online course.
A student team examined parked cars in four different suburban shopping malls. One hundred vehicles were examined in each location. At alph=.05, does vehicle type vary by mall location? State hypothesis, show degree of freedom, find critical value of chisquare and interpret p-value.
Vehicle type,Somerset,Oakland,Greatlakes,Jamestown,Row Total
Car,44,49,36,64,193
Minivan,21,15,18,13,67
Full-sizedVan,2,3,3,2,10
SUV,19,27,26,12,84
Truck,14,6,17,9,45
Col Total,100,100,100,100,400
Thank you in advance.
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Question 133654: Note: Use the five-step hypothesis testing procedure to solve the following exercise.
[show the answer for each of the five steps]
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 Pittsburgh.
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 133690This question is from textbook Fundmentals of Alegebraic Modeling
: Using data from any year in the last 10 years, estimate the probability a newborn baby will be female.
The total population os 2001 is 281,421,906
total numbers of females born in 2001 is 143,368,343
143,368,343,/ 281,421,906 = 0.509This question is from textbook Fundmentals of Alegebraic Modeling
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Question 133760: Hi, Can someone help me with these 2 questions, I'm a little confused as to what I am suppose to be doing.
1. You are the incoming inspector for potato chips – you are to ensure that each bag has 16 ounces or more in it. You want your testing to be at the level of significance of 0.05. You pull a sample of 49 bags of chips from a recent truckload. Your sample statistics are:
x-bar (the sample mean) = 15.9 ounces
s ( the sample standard deviation) = 0.35 ounces
(a) what is the null and alternative hypothesis
(b) one or two tailed test ??
(c) what is the critical z value for your test at the 0.05 level of significance??
(d) what is the calculated z value ??
(e) what is your decision about the load of potato chips ??
-- reject ?? -- not-reject ??
(a) Ho : μ <= 16 Vs H1 : μ < 16 (Left tailed test)
(b) One tailed test
(c) Critical z = 1.645
(d) Test Statistics:
z = follows N(0,1)
= -2
where
x bar=15.9 n=49 s=0.35 μ= 16
(e) Rejection Rule
Critical Value = -1.645
Thus we reject H0 if z < -1.645
As z = -2 < -1.645 we reject H0.
At the 5% level of significance, the data provides enough evidence to reject the null hypothesis. Thus we conclude that each bag has less than 16 ounces.
2. An owner of a fast food restaurant reported to corporate headquarters that the average bill paid by his customers in the last quarter was $6.20 and that the standard deviation was $1.90. Not knowing exactly what the effect would be, headquarters suddenly launched a nationwide promotional campaign featuring a large quantity discount for a multi-sandwich purchase. The stubs from the next 81 purchases at the owner’s franchise after the campaign was launched averaged $6.65.
Conduct the 5 step hypothesis test at a level of significance of 0.05 to determine if the promotion increased the average bill amount
Ans.
• To Test
Ho : μ= 6.20 Vs H1 : μ > 6.20 (Right tailed test)
• Level of significance = 0.05
• Test Statistics:
z = xbar-μ/SE follows N(0,1)
= 2.13
where
xbar =6.65 n=81 sd=1.9 μ= 6.2
• P-value = P(z > 2.13) = 0.0165
Since P-value of 0.0165 < 0.05 we reject H0.
It is statistically significant
• Rejection Rule
Critical Value = 1.645
Thus we reject H0 if z > 1.645
As z = 2.13 > 1.645 we reject H0.
• Conclusion
At the 5% level of significance, the data provides enough evidence to reject the null hypothesis. Thus we conclude that the promotion increased the average bill amount.
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Question 134271: Answer the following questions, inserting values from the ANOVA table below.
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?
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Question 134229This question is from textbook Applied Statistics in Business and Economics
: An auditor reviewed 25 oral surgery insurance claims from a particular surgical office, determining that the mean out-of-pocket patient billing above the remibursed amount was $275.66 with a standard deviation of $78.11. (a) At the 5% level of significance, does this sample prove a 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?
Thanks for your help.
Applied Statistics in Business and Economics
David P. Doane, Lori E. Seward
Publisher: Boston : McGraw-Hill/Irwin, c2007.
ISBN: 0072966939 DDC: 519.5 LCC: HF1017 Edition: (student ed.) This question is from textbook Applied Statistics in Business and Economics
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Question 134174: According to a study, brain weight of men in country A are normally distributed with mean 1.40 kg and standard deviation 0.13kg. Apply the 68.26-95.44-99.74 to fill in the blanks
99.74 of men in country A have weights btw _&_
99.74 % of men in country A have brain weights btw __kg&__kg
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Question 134144: 60. Owens Orchards sells apples in a large bag by weight. A sample of seven bags contained the following numbers of apples: 23, 19, 26, 17, 21, 24, 22.
a. Compute the mean number and median number of apples in a bag.
_
b. Verify that (X – X) = 0.
The mean (average) of 17,19,21,22,23,24, and 26 is: 21.714285.
The median of this set is: 22.
This set has no mode.
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Question 133947: An owner of a fast food restaurant reported to corporate headquarters that the average bill paid by his customers in the last quarter was $6.20 and that the standard deviation was $1.90. Not knowing exactly what the effect would be, headquarters suddenly launched a nationwide promotional campaign featuring a large quantity discount for a multi-sandwich purchase. The stubs from the next 81 purchases at the owner’s franchise after the campaign was launched averaged $6.65.
Conduct the 5 step hypothesis test at a level of significance of 0.05 to determine if the promotion increased the average bill amount.
Click here to see answer by stanbon(26259) |
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