Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 147460: Faced with the rising fax costs, a firm issued a guideline that transmission of 10 pages or more should be sent by 2-day mail instead. Exceptions are allowed, but they want the average to be 10 or below. The firm examined 35 randomly chosen fax transmissions during the next year, yielding a sample mean of 14.44 with a standard deviation 4.45 pages. (a). At the .01 level of significance, is the true mean greater that 10? (b) Use Excel to find the right-tail p-value.
Click here to see answer by stanbon(57250)  |
Question 146629: 31. What can we conclude if the coefficient of determination is 0.94?
A) Strength of relationship is 0.94
B) Direction of relationship is positive
C) 94% of total variation in one variable is explained by variation in the other variable
D) All of the above are correct
E) None of the above is correct
Click here to see answer by nanaktutors@yahoo.com(8) |
Question 147978: 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.
a) Write the fitted regression equation.
Y = 30.7963 + 0.0343X
--------------------------------
(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.
df = 33 ; critical value is 2.035 (see page 782)
(c) What is your conclusion about the slope?
Since the p-value is 0.0068 (less than 1%), the true value is not zero.
------------------------
(d) Interpret the 95 percent confidence limits for the slope.
We are 95% confident that the slope is between 0.0101 and 0.0584
----------------------
(e) Verify that F = t2 for the slope.
2.889^2 = = 8.346321 (rounded is 8.35)
Click here to see answer by stanbon(57250) |
Question 147978: 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.
a) Write the fitted regression equation.
Y = 30.7963 + 0.0343X
--------------------------------
(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.
df = 33 ; critical value is 2.035 (see page 782)
(c) What is your conclusion about the slope?
Since the p-value is 0.0068 (less than 1%), the true value is not zero.
------------------------
(d) Interpret the 95 percent confidence limits for the slope.
We are 95% confident that the slope is between 0.0101 and 0.0584
----------------------
(e) Verify that F = t2 for the slope.
2.889^2 = = 8.346321 (rounded is 8.35)
Click here to see answer by assante10(1) |
Question 147977: 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.
Click here to see answer by stanbon(57250) |
Question 148409: the probability that San Francisco plays in the next Super Bowl is nine times the probability that they do not play in the next Super Bowl. The probability that San Francisco plays in the next Super Bowl plus the probabilty that they do not play is 1. What is the probablity that San Francisco plays in the next Super Bowl?
Click here to see answer by stanbon(57250) |
Question 148331: Probability is not my high point. I have tried to come up with an answer, but I need assistance, please. Here is the question:
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.
Thank you!
Click here to see answer by stanbon(57250) |
Question 148687: 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(57250) |
Question 148467: 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? Crash1Crash 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 stanbon(57250) |
Question 148777: Does anyone out there is statistics land have a clue how to figure this problem out??? I would appreciate any help. Thank you in advance!
At wind speeds above 1000 cm/sec, significant sand-moving events begin to occur. Wind speeds below 1000 cm/sec deposit sand and wind speeds above 1000 cm/sec move sand to new locations. The cyclic nature of wind and moving sand determines teh shape and location of large dunes. At a test site, the prevailing direction of the wind did not change noticeably. However, the velocity did change. Sixty wind speed readings gave an average velocity of x(bar)=1075 cm/sec. Based on long term experience, sigma (standard deviation)can be assumed to be 265 cm/sec.
Find a 95% confidence interval for the population mean wind speed at this site AND does the confidence interval indicate that the population mean wind speed is such that the sand is always moving at this site. Explain.
Click here to see answer by stanbon(57250) |
Question 148808: The mean weight of newborn infants at a community hospital is 6.6 pounds. A sample of seven infants is randomly selected and their weights at birth are recorded as 9.0, 7.3, 6.0, 8.8, 6.8, 8.4, and 6.6 pounds.
Click here to see answer by stanbon(57250) |
Question 148815: Please Help!
The home run percentage is the number of home runs per 100 times at bat. A random sample of 43 professional baseball players gave the following data for home run percentages. x(bar)=2.29 and s=1.40.
Compute a 99% CI for the population mean of home run percentages for all professional baseball players AND: The home run percentages for 3 professional players are:
Tim Huilett, 2.5 Herb Hunter, 2.0 Jackie Jensen, 3.8
Examine your CI's and describe how home run percentages for these players compare to the population average.
Click here to see answer by stanbon(57250) |
Question 148859: Greetings,
Statistics question. questeion posed by an English as a second language statistics intructor.
2) Can the bell shaped curve on the graph of normal distribution cross the x-axis? Explain your answer.
Thanks for the help,
Dennis Wade
Click here to see answer by stanbon(57250) |
Question 148919: Are the answers right?
University of Phoenix Material
Parametric and Nonparametric Data Identification Assignment
Label each of the following situations “P” if it is an example of parametric data or “NP” if it is an example of nonparametric data.
1. A manufacturer produces a batch of memory chips (RAM) and measures the mean-time-between-failures (MTBF). The manufacturer then changes a manufacturing process and produces another batch and again measures the MTBF. Did the change to the process improve the MTBF? P____
2. From a written survey where the respondents were asked to rate an individual on a scale of 1 to 5, one group rated an individual a 3.7, another group rated the individual a 4.3. Is the difference statistically significant? __NP__
3. A catering company is buying equipment in order to set up their own store. They have a choice of two ovens that they can purchase for the store. The used oven is $100 less than the new oven, but its heating calibration is off by 20 degrees. Which one is a better buy for them? P____
4. Jim Smith owns three real estate offices in Anytown. He has decided to open one more office, but he cannot decide between Hometown or Uptown as the town where he wants to locate. He will be comparing the mean number of homes sold per real estate agent, and the mean commission percentage earned by agents in the two towns to make his decision. _P___
5. A study to determine if job absenteeism is distributed evenly over the week. __NP__
6. Mel’s Diner has been surveying their customers for the past couple of years about their dining experience in the restaurant. The survey uses a scale of one to five, five being best to indicate customer satisfaction. Mel’s customer satisfaction averaged 2.5 last year, but this year it is 2.9. Is this difference statistically significant? _NP___
7. Sally’s Beauty Salon just opened for business. Sally assigns the stylists customers on a rotation basis so that everyone is kept busy all day. One month after she opened the salon, Sally’s customer count for each stylist was (a) 20 customers; (b) 30 customers; (c) 15 customers; and (d) 25 customers. Has Sally been fair in how she allocates customers to each of the stylists? _P___
8. A comparison of salaries between male and female employees in the same organization. _NP___
Click here to see answer by stanbon(57250) |
Question 149095: A drawer contains red socks, black socks, and white socks. What is the least number of socks that must be taken out of the drawer to be sure of having 7 matching pairs of socks? Answer choices of 9, 14,16,17; the correct answer is 16, but I don't understand how to set this problem up! Please help
Click here to see answer by scott8148(6628)  |
Question 149493: In a shop there are 20 customers, 18 of whom will make a purchase. If three customers are selected, one at a time, at random, what is the probability that all will make a purchase? Is it 0.7717, 0.7605, 0.8524, or 0.8808.
Please help
Click here to see answer by Edwin McCravy(8882)  |
Question 149493: In a shop there are 20 customers, 18 of whom will make a purchase. If three customers are selected, one at a time, at random, what is the probability that all will make a purchase? Is it 0.7717, 0.7605, 0.8524, or 0.8808.
Please help
Click here to see answer by stanbon(57250) |
Question 149737: Still struggling with this one. There are 20 customers. 18 will make a purchase. If three customers are selected, one at a time, what is the probability that all will make a purchase? Instructor says the answer is one of four 1)0.7717, 2) 0.7605 3) 0.8524 or 4)0.8808
Please help
Click here to see answer by scott8148(6628) |
Question 149898: This is an intro to probability chapter in a book called Applied mathmatics. The book is a combo of two diferent books especially made for my school.
This is the problem:
Find (2n+2)!/(2n)!
I know how to do algebra, my problem I believe is because of the ! symbol. I have just been introduced to it and understand the concept , but not how it works in an agebraic expression.
Itried soving for n but don't know what to do with the !
ineed to understand the steps involved.
this is the answer:
4n2 +6n + 2
thanks in advance for any help.
heidi
Click here to see answer by jim_thompson5910(28504) |
Question 149900: I don't know where to start with this one.
It is in a chapter called intro to probability.
nC8 = nC7 Find N
the answer is: n=15
the 2 Ns and the numerals 7 and 8 are all subscripts.
Ineed to understand the steps involved. I know how to use basic algebra, it is the subscripts I don't know how to deal with.
thanks in advance for any help.
Heidi
Click here to see answer by jim_thompson5910(28504) |
Question 149928: Here is the problem:
Quality Control:
Suppose that 10 computer chips are drawn from a box containing 12 good chips and 4 defective chips. What is the probability that
a. exactly 4 of the chips are defective
b. all 10 of the chips are good
c. exactly 8 of the chips are good
the answers are:
a. 924/8008
b. 66/8008
c. 2970/8008\
I tried using the nCr formula. I am sure this is the right one(not really sure or I would not be writing this) only i can't figure out which numbers to put where.
this is what I did:
working on a.
10!/4!(10-4)! = came up with 210
thanks in advance for any help.
Heidi
ps where do i find the thank you form. can't find it.
Click here to see answer by stanbon(57250) |
Question 149621: 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? (Data are from Consumer Reports 56, no. 8 [August 1991], p. 519.)
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(57250) |
Question 149480: 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? (Data are from Consumer Reports 56, no. 8 [August 1991], p. 519.)
Cola
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(57250) |
Question 149995: If anyone could help with this, that would be great.thanks
Here is the problem:
Mutual Funds
The retirement plan for a company allows employees to invest in 10 different mutual funds. If Sam selected 4 of these funds at random, and 6 of the 10 grew by at least 10% over the last year, what is the probability that 3 of Sam's 4 funds grew by at least 10% last year?
i have tried many things nothing works.
Heidi
Click here to see answer by scott8148(6628) |
Question 150064: I'm re-submitting this question because i realized i didn't type in my email address correctly :)
Please help with following problem from Research & Evaluation class:
The area to the right of z=+2.43 and to the left of z=-3.01 is closest to which of the following:
a)0.0076
b)0.0092
c)0.0095
d)0.0099
e)0.0718
Thank you,
Christi
Click here to see answer by stanbon(57250) |
Question 150086: 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.
Click here to see answer by stanbon(57250) |
Question 150203: 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?
Click here to see answer by stanbon(57250) |
Question 150202: Faced with rising fax costs, a firm issued a guideline that transmissions of 10 pages or more should be sent by 2-day mail instead. Exceptions are allowed, but they want the average to be 10 or below. The firm examined 35 randomly chosen fax transmissions during the next year, yielding a sample mean of 14.44 with a standard deviation of 4.45 pages. (a) At the .01 level of significance, is the true mean greater than 10? (b) Use Excel to find the right-tail p-value.
Click here to see answer by stanbon(57250) |
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