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Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 180315: An auditor reviewed 25 oral surgery insurance claims from a particular surgical office, determining that the mean out-of-pocket patient billing above the reimbursed amount was $275.66 with a standard deviation of $78.11. (a) At the 5 percent 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?
Click here to see answer by stanbon(26259)   |
Question 180363: Ron has a 53% chance of receiving an A grade in geology, a 43% chance of receiving an A grade in mathematics, and a 76% chance of receiving an A grade in geology or mathematics (or both). Find the probability that he receives A grades in both geology and mathematics.
Click here to see answer by stanbon(26259) |
Question 180477: The manufacturer of Winston Tire Company claims its new tires last for an average 40,000 miles. An independent testing agency road-tested 20 tires to substantiate the claim made by the Winston Tire Company. The sample mean was 39,000 miles with a sample standard deviation of 5,000 miles. Using the .05 level of significance and the five-step hypothesis testing procedure, determine if there is reason to reject the claim made by Winston Tire Company and conclude that tires last for less than 40,000 miles.
My question: Am I on the right track and/or if not, what are the steps and formulas to use to solve for this?
I came up with:
H0: (Mu) = 40,000
H1: (Mu) not equal to 40,000
Z = 39,000 – 40,000/5,000/ sqrt 20 = - 4
I would say:
Reject the null in favor of the alternative, since – 4 falls in the rejection region.
Thank you
Click here to see answer by stanbon(26259) |
Question 180480: The data in the table that follows was collected by a large car manufacturer concerning a new prototype car called the CIELO. Thirty carefully selected respondents were shown the car and fully briefed about its capabilities. Here is the data, which includes age (intervally scaled), sex (nominal), social status (interval scale ranging from 10, low status, to 30, high status), attitude toward CIELO (interval scale ranging from 6, negative attitude, to 30, positive attitude) and intention to purchase CIELO (nominal, yes or no).
Is there any difference in male and female attitude scores toward the CIELO? Is there anything unusual about this data? Please note that we have to setup a hypothesis test of the difference in two population (female respondents and male respondents) means (attitude scores).
RESPONDENT #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
AGE
20
19
34
23
42
55
24
26
35
41
43
51
56
62
43
51
28
19
24
26
28
35
38
23
42
41
30
29
19
26
SEX
M
F
M
M
M
F
F
M
F
M
F
M
M
F
F
F
M
M
M
F
F
M
F
M
F
F
F
M
M
F
SOCIAL STATUS
15.6
17.5
28.2
24.6
16.5
12.2
12.5
29.6
27.6
23.2
21.2
20.2
19.4
18.6
10.2
14.3
12.6
14.8
29.6
26.5
23.2
17.9
19.9
20.1
18.6
18.6
24.6
26.6
14.5
12.9
ATTITUDE SCORE
16
15
14
6
28
24
19
14
23
16
26
28
14
12
11
10
22
24
19
18
20
23
23
25
17
17
16
13
22
21
INTENTION TO PURCHASE
Y
Y
N
N
Y
N
Y
N
N
N
Y
N
N
Y
Y
N
Y
N
N
Y
N
N
N
Y
N
N
Y
N
Y
N
My question: Am I on the right track and/or if not can you please show me how to set up the hypothesis test and solve for it?
I got this:
Female: 272/15 = 18.133
Male: 284/15 = 18.933
H0: (Mu) less than or equal to 18
H1: (Mu) greater than 18
Small Sample
18.133 – 18.933/Sqrt 30(squared)*(1 over 15 + 1 over 15) = (0.8) / 900 * 2 over 15 = 120
(-0.8)/Sqrt 120 = (-0.8) / 10.954 = 0.073
Large Sample
18.133 – 18.933/Sqrt 30(squared) / 30(squared)over 15 / 30 (squared) over 15
= (0.8)/900 over 15 + 900 over 15
= (0.8)/ 60+60 = (0.8) / 120 = 0.006
Q: I am not sure if these are the right samples to use or if I should use a paired “t” sample? (below)
15
30 / sqrt (?)
Thank you
Click here to see answer by stanbon(26259) |
Question 180515: Suppose that 53% of the women who gave birth at a certain hospital last year were over 30 years old, and that 30% were unmarried. If 28% of the women were both unmarried and over 30, what is the probability that a woman who gave birth at the hospital was over 30 or unmarried (or both)?
Click here to see answer by stanbon(26259) |
Question 180539This question is from textbook Chapter 11 Skill practice
: Can you explain these problem?
1.) When text messaging on a telephone, pressing a 3 types D, E, F, or 3. Pressing a 7 types P, Q, R, S, or 7. How many messages are possible by pressing a 3, a 7, and then a 3?
11.) What is the probability that a random 2-digit number is a multiple of 7?
13.) A mother is making different lunches for each of her 3 children. If each child grabs a lunch bag at random, what is the probability that all 3 children will get the correct bag?
21.) Two number cubes are rolled--one blue and one yellow. Find the probability that the yellow cube is even, and the sum is 7. Explain why the events are dependent.
Please answer me as soon as you could. Thank you for your help. This question is from textbook Chapter 11 Skill practice
Click here to see answer by stanbon(26259) |
Question 180536: A rainstorm in Portland, Oregon, wiped out the electricity in 7% of the households in the city. Suppose that a random sample of 50 Portland households is taken after the rainstorm.
A Estimate the number of households in the sample that lost electricity by giving the mean of the relevant distribution (that is, the expectation of the relevant random variable). Do not round your response.
B Quantify the uncertainty of your estimate by giving the standard deviation of the distribution. Round your response to at least three decimal places.
Click here to see answer by stanbon(26259) |
Question 180577This question is from textbook
: 1.)The blue cube show a multiple of 3, and the sum is 8.
>>>P(blue multiple of 3)=2/6=1/3
>>>P(sum is 8 | blue multiple of 3 ) =2/12=1/6
>>>P(blue multiple of 3 and sum is 8)=
P(blue multiple of 3)*P(sum is 8 | blue multiple of 3) = (1/3)*(1/6)=1/18
My question: Do you know how 2/6 and 2/12 came from?
Can you explain?
Please answer me as soon as you could.
Thank you for your help.This question is from textbook
Click here to see answer by stanbon(26259) |
Question 180621: Not all visitors to a certain company's website are customers. In fact, the website administrator estimates that about 12% of all visitors to the website are looking for other websites. Assuming that this estimate is correct, find the probability that, in a random sample of 5 visitors to the website, exactly 4 actually are looking for the website.
Round your response to at least three decimal places.
Click here to see answer by stanbon(26259) |
Question 180619: I have found a solution already but I am still having a problem with (b) in the problem.
What formula do I use to find the answer.
To test the hypothesis that students who finish an exam first get better grades, Professor Hardtack
kept track of the order in which papers were handed in. The first 25 papers showed a mean score of
77.1 with a standard deviation of 19.6, while the last 24 papers handed in showed a mean score of
69.3 with a standard deviation of 24.9. Is this a significant difference at α = .05? (a) State the
hypotheses for a right-tailed test. (b) Obtain a test statistic and p-value assuming equal variances.
Interpret these results. (c) Is the difference in mean scores large enough to be important? (d) Is it reasonable
to assume equal variances? (e) Carry out a formal test for equal variances at α = .05, showing
all steps clearly.
Click here to see answer by stanbon(26259) |
Question 180108: Suppose that 48% of the women who gave birth at a certain hospital last year were over 30 years old, and that 46% were unmarried. If 65% of the women were over 30 or unmarried (or both), what is the probability that a woman who gave birth at the hospital was both unmarried and over 30 ?
Click here to see answer by stanbon(26259) |
Question 180823: Suppose that the New England Colonials baseball team is equally likely to win a game as not to win it. If 5 Colonials games are chosen at random, what is the probability that exactly 4 of those games are won by the Colonials?
Round your response to at least three decimal places.
Click here to see answer by stanbon(26259) |
Question 180837: A machine that manufactures automobile parts is estimated to produce defective parts 8% of the time. If this estimate is correct, and 10 parts produced by this machine are randomly selected, what is the probability that more than 1 turn out to be defective? Round your answer to four decimal places.
Click here to see answer by stanbon(26259) |
Question 180897: How can I proceed to solve this problem? Thank you.
In establishing warranties on HDTV sets, the manufacturer wants to set the limites so that few will need repair at manufacturer expense. On the other hand, the warranty period mst 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 expensive?
Click here to see answer by user_dude2008(715) |
Question 180889This question is from textbook
: A license plate is to consist of two letters followed by three digits. How many different license plates are possible if the first letter must be a vowel, and repetition of letters is not permitted, but repetition of digits is permitted? This question is from textbook
Click here to see answer by edjones(3292)  |
Question 181002: A home security system is designed to be triggered in 96% of attempted burglaries. If 7 homes equipped with such a system experience an attempted burglary, find the probability that at least 6 alarms are triggered. Round your answer to four decimal places.
Click here to see answer by stanbon(26259) |
Question 181008: A survey showed that 24% of college students read newspapers on a regular basis and that 82% of college students regularly watch the news on TV. The survey also showed that 21% of college students both follow TV news regularly and read newspapers regularly.
(a) What is the probability that a student watches TV news regularly, given that he or she regularly reads newspapers? Round your answer to 2 decimal places.
(b) What is the probability that a randomly selected college student reads newspapers regularly, given that he or she watches TV news regularly? Round your answer to 2 decimal places.
Click here to see answer by stanbon(26259) |
Question 181062: The following data are the maximum temperatures (in degrees Fahrenheit) of 18 cities in the United States measured on the same day.
83,67,56,71,76,52,57,84,54,64,74,63,51,54,75,65,55,71
construct a box-and-whisker plot for the data.
Click here to see answer by eperette(173) |
Question 181061: Several years ago, the state of California launched an aggressive advertisement campaign against smoking. We've interviewed students from 17 college campuses in California and recorded for each campus the percentage of students who claimed that they had encountered at least one anti-smoking advertisement on campus in the past month. Here are those percentages:
59,58,49,53,32,27,41,52,37,51,30,25,58,60,32,37,46
construct a box-and-whisker plot for the data
Click here to see answer by eperette(173) |
Question 181078: 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.
Question out of Textbook Applied Statistics by Doane and Seward, 10.56 chapter 10. ISBN-13 978-0-07-296693-0
Click here to see answer by stanbon(26259) |
Question 181139: Conditional probability: Basic
At a certain college, 47% of the students are female, and 21% of the students major in finance. Furthermore, 12% of the students both are female and major in finance.
(a) What is the probability that a randomly selected finance major is female? Round your answer to 2 decimal places.
(b) What is the probability that a randomly selected female student majors in finance? Round your answer to 2 decimal places.
Click here to see answer by stanbon(26259) |
Question 181180: Suppose that a classroom has 4 sets of lights. The probability that one of the lights work is 0.6. Suppose that each light works independently of the others. What is the probability that none of the lights work? Round your answer to two decimals places.
Click here to see answer by stanbon(26259) |
Question 181119This question is from textbook
: 4. In tests of a computer component, it is found that the mean time between failures is 530 hours. A modification is made which is supposed to increase the time between failures. Tests on a random sample of 10 modified components resulted in the following times (in hours) between failures.
518- 548- 561- 523- 536- 499- 538- 557- 528- 563
a. Determine the mean and standard deviation for the data set. (5 points)
b. At the 0.01 level of significance, test the claim that for the modified components, the mean time between failures is greater than 530 hours. You may assume the time between failures is normally distributed. (5 points)
This question is from textbook
Click here to see answer by stanbon(26259) |
Question 181083: The following data are the maximum temperatures (in degrees Fahrenheit) of 18 cities in the United States measured on the same day.
66,68,52,84,70,80,80,73,53,54,50,70,82,83,67,81,51,85
construct a box-and-whisker plot for the data.
Click here to see answer by stanbon(26259) |
Question 181028: 1. An apple juice manufacturer develops a new juice concentrate. This new product is a) more convenient, b) higher in quality, and c) less expensive than conventional apple juice. The marketing manager needs to decide whether advertising should stress convenience, quality, or price. A pilot study is done in three small cities each promoting one of the different attributes of the new juice concentrates. Then the mean sales for each city are compared. Does the approach to advertising affect sales? That is, is there a difference in the mean sales in the three cities? An ANOVA table, shown below provides the results of the sales surveys. Test at alpha = .01.
ANOVA table for one way analysis of variance:
Source of D.F. Sum of Squares Mean Square F-statistic
Treatment k-1 SST MST=SST/(k-1) F=MST/MSE
Error n-k SSE MSE=SST/(n-k)
Total n-1 SS(Total)
Source of D.F. Sum of Squares Mean Square F-statistic calc
Treatment 2 57,512.2 28,756 3.23
Error 58 506,983.5 8,894
Total 60 564,495.7
Use the five-step hypothesis-testing procedure.
1. State the null hypothesis:
2. State the alternate hypothesis:
3. State the decision rule (I will reject the null hypothesis if the calculated value of the test statistic, F, is (greater than, or less than, or both)_______(then fill in the value)_______.
4. State the value of the test statistic
5. What is your decision regarding the null hypothesis (accept or reject)?
6. What does this say about advertising’s affect on sales?
Click here to see answer by stanbon(26259) |
Question 181215This question is from textbook
: A test of sobriety involves measuring the subjects motor skills. Twenty randomly selected sober subjects take the test and produce a mean score of 41.0 with a standard deviation of 3.7. At the 0.01 level of significance, test the claim that the true mean score for all sober subjects is equal to 35.0. You may assume that sobriety is normally distributed.This question is from textbook
Click here to see answer by stanbon(26259) |
Question 181239: Hi,
can you please explain the steps (formulas) "in detail" of finding the p-value uaing a z-test, and a one tailed test and a two tailed test.
Ex: z= 1764 -1750/ 70/ sqrt 150 = 2.4494 ~ 2.449
Also how do you find a critical value, do you follow the same steps?
I have this example but I don't understand where 0.937 came from or what the P is and why there are the <= symbols when doing addition?:
=P(Z<= -1.531) + P(Z>= 1.531)
=P (Z<= -1.531)+ (1-P(Z< 1.531))
=0.063 + (1-0,937)
=0.126
Thank you
Click here to see answer by stanbon(26259) |
Question 181222This question is from textbook
: A manufacturer makes ball bearings that are supposed to have a mean weight of 30g. A retailer suspects that the mean weight is actually less than 30g. The mean weight for a random sample of 16 ball bearings is 29.5g with a standard deviation of 4.1g. At the 0.05 significance level, test the claim that the mean is less than 30g. You may assume the ball bearing weights are normally distributed. Use the traditional method to make your decision.This question is from textbook
Click here to see answer by stanbon(26259) |
Question 181294This question is from textbook
: Claim: The mean time between uses of a TV remote control by males during commercials equals 5.0 seconds. Find the test statistic, p-value, critical value(s), and state the final conclusion.
Sample data: n = 80, x-bar = 5.25 sec. Assume that s = 2.50 sec and the significance level is a = .01. (Use p-value approach)
This question is from textbook
Click here to see answer by stanbon(26259) |
Question 181383: Hi,
Can you please help me solve for:
Advertisers need to know which age groups are likely to see their ads. Purchasers of 120 copies of Cosmopolitan are shown by age group.
(a) Make a bar chart and describe it.
(b) What would be the appropriate Null and Alternate Hypotheses?
(c) Calculate expected frequencies for each class.
(d) Perform the chi-square test for a uniform distribution. At α = .01, does this sample contradict the assumption that readership is uniformly distributed among these six age groups?
(See J. Paul Peter and Jerry C. Olson, Consumer Behavior and Marketing Strategy, 9th ed. [McGraw-Hill, 2004], p. 300.)
Purchaser Age Units Sold
18~24 38
25~34 28
35~44 19
45~54 16
55~64 10
65+ 9
Total 120
Thank you,
Click here to see answer by stanbon(26259) |
Question 181411: Data Analysis, Statistics, and Probability (worksheet)
Questions:
While answering the questions please tell me how to get the answer. Thanks.
1.A menu has 3 appetizers, 5 salads, 7 entrees, and 4 desserts. How many different meals can be made from this menu?
A.420
B.840
C.150
D.270
2.The Personal Identification Number for a bank must be a four-digit number. Each digit can be a number between zero and nine. How many possible Personal Identification Numbers are there?
A.10
B.100
C.1,000
D.10,000
3.A man tosses a six-sided die three times. How many possible outcomes are there?
A.18
B.6^2
C.6^3
D.6^4
4.A piano club with 23 members needs a president, vice president, tutor, and treasurer. How many ways can the club choose the 4 officers.
Please help, thanks.
Click here to see answer by solver91311(5072)  |
Question 181417: This is a practice worksheet no book. Sorry
CHI Square
Students in grades 4-6 were asked whether good grades, athletic ability, or popularity was important to them. A two way table separating the students by grade and choice or most important factor is shown below"
Grade
Goals 4 5 6 Total
____________________________
Grades 49 50 69 168
Popular 24 36 38 98
Sports 19 22 28 69
_____________________________
Total 92 108 135 335
a. State the null and alternate hypothesis.
Ho:________ H1:__________
b. State the decision rule.
____________________________________________________
c. Compute the value of the test statistic. For Chi Square first calculate the expected values.
Original Table
Grade
Goals 4 5 6 Total
______________________________
Grades 49 50 69 168
Popular 24 36 38 98
Sports 19 22 28 69
____________________________
Total 92 108 135 335
calculate the expected values.
? 2
2 (observed - expected)
X = ___________________ calculate
d. compute P value
e. What is your decision reguarding the null hypothesis?
expected
Click here to see answer by stanbon(26259) |
Question 181606: 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?
Click here to see answer by stanbon(26259) |
Question 126817: I tried to find the answer to this question, but was totally confused.
One card is selected at random from a standard 52-card deck of playing cards. Find the probability that the card selected is not a spade.
Click here to see answer by jm(1) |
Question 181762: 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.
Click here to see answer by stanbon(26259) |
Question 181873: The probability that a particular type of smoke alarm will function properly and sound an alarm in the presence of smoke is 0.8. You have 2 such alarms in your home and they operate independently.
What is the probability that both sound an alarm in the presence of smoke is
Click here to see answer by stanbon(26259) |
Question 181884: Hi,
Can you please help me solve for this problem, it is from Doane−Seward: Applied
Statistics in Business and Economics, ch. 11. My guess was to find the mean of each hospital time. Example: Hospital A 10+19+5+26+11/5 = 14.2
But I feel like there is more to the problem, am I on the right track?
Problem:
The waiting time (in minutes) for emergency room patients with non-life-threatening injuries was measured at four hospitals for all patients who arrived between 6:00 and 6:30 PM on a certain Wednesday. The results are shown below. Research question: Are the mean waiting times the same for emergency patients in these four hospitals?
Emergency Room Waiting Time (minutes)
Hospital A - 10, 19, 5, 26,11
Hospital B - 8, 25, 17, 36
Hospital C - 5, 11, 24, 16, 18, 29, 15
Hospital D - 0, 20, 9, 5, 10, 12
Thank you
Click here to see answer by vleith(1977) |
Question 181886: Hi Tutors! I have a really hard problem that I'm stuck on! Please help me how to solve it!
In a warehouse, accidents have been taking place at the rate of 2 every 3 months.
a) What probability distribution is most likely to model the number of accidents in a 3-month period? Give reasons for your choice that are related to the problem and give any parameters for the distribution.
b) Find the mean and standard deviation of the number of accidents per year and what is the percentage of months with no accidents?
c) If a month is chosen at random, find the probability of at least one accident.
I would really appreciate if tutors can help!! Thank you!!!!
Click here to see answer by stanbon(26259) |
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