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Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 142507: Determine if the events ae independent. Explain you answers.
A.) You roll two number cubes. One shows a 3 Th other shows a 1.
B.) You draw a ed marble fom hte bag containg red and yellow marbles. You do no put the marble back. you draw another red marble.
Click here to see answer by rapaljer(3620)   |
Question 142549: Exercise using Excel
The School Committee members of a midsized New England city agreed that a strict
discipline code has caused an increase in the number of student suspensions. The
number of suspensions for September 1992 - February 1993 for a sample of the schools is provided below. {Data}
The average number of suspensions for the previous year mean{X bar} = 130.5 and the Standard deviation {STDEV}
was 158.2
(a) Set up the null and alternative hypothesis to test if the averave number of suspensions
has changed.
(b) Test your hypothesis with alpha = 0.05.
(c) Find the p value.
(d) Display the data in an Excel Chart to see if it is reasonable to assume that the underlaying population
distribution is normal.
(e) Based on the p value, what can you conclude about the average number of suspensions?
Data:
Suspensions
Central 245 a) - c) mu = 195
MCDI 1 Step 1 H(0) mean equal 130.5
Chestnut 65 H(A) mean not equal 130.5
Duggan 133 Sigma is given as = 158.2
Kennedy 97 Step 2 Critical Values (Z) = +/-1.96 because alpha is 0.05
Forest Park 149 (n)^0.5 Z P(Z<-1.352) p = 2*P(Z<-1.352) = 2*0.0885
Putnam 1024 Step 3 Test Statistic Z 3.317 Calculate Z here in cell H25.
Kiley 56 p value = 0.177
Central Academy 254 Why is Z minus?
Commerce 114 Step 4/5 d) See Below.
Bridge 7 e) What do you think?
STDEV= 287.15
mu = 195.00
ReOrder
MCDI 1
Bridge 7
Kiley 56
Chestnut 65
Kennedy 97
Commerce 114
Duggan 133
Forest Park 149
Central 245
Central Academy 254
Putnam 1024
Click here to see answer by stanbon(26259) |
Question 142565This question is from textbook
: Find a confidence interval for μ assuming that each sample is from a normal population.
a. ¯x = 14, σ = 4, n = 5, 90 percent confidence
b. ¯x = 37, σ = 5, n = 15, 99 percent confidence
c. ¯x = 121, σ = 15, n = 25, 95 percent confidenceThis question is from textbook
Click here to see answer by stanbon(26259) |
Question 142631: I need a little guidance here. My grader stated a lot of my work was good but below the line there are some comments about what I did wrong. Please show me the error of my ways. :)
Given:
A potato chip company packages its potato chips into 12.0 ounce bags. You find it hard to believe that the bag contains enough potato chips to weigh 12.0 ounces and would like to make an official complaint. Before doing so, you decide to run an experiment so that you can have some confidence that the company’s claim is incorrect. Over the next several months you buy 30 bags of potato chips and weigh the contents of each one. You discover that the mean weight is 11.9 ounces with a standard deviation of 0.4 ounces. You decide that you will only complain if you can be 95% sure that the bags do not contain at least 12.0 ounces of potato chips. You decide to construct a hypothesis test.
Task:
Determine if this is a one-tailed or two-tailed test. Justify your decision.
This is a one-tailed test. This is because you believe the average weight is below the manufacturer’s stated weight of 12 ounces per bag.
State the null hypothesis and alternative hypothesis. Your null hypothesis should assume the company’s claim is correct.
Ho: average weight = 12
Ha: average weight<12
Define the term Type I error and explain what a Type I error is in terms of this problem.
Type I error means that you reject the null hypothesis when it is true. In this problem, you reject that each bag of chips has an average weight of 12 ounces when it is in fact true.
--------------------------------------------------------------------------------
Define the term level of significance and identify the level of significance for this problem.
My answer:
Significance level means that we reject the null hypothesis if the P-value is less than or equal to that number. This number is usually .05 and is in this case as well, since the given states you want to be 95% sure. The level of significance represents the probability of a Type I error.
Grader comment:
The response describes how the level of significance is used. What does it represent? It is the probability of what?
Calculate the test statistic as a z-score. Show all relevant work.
Grader Comment: This is not the formula to evaluate the 30-bag sample. Please also note that the standard deviation is not .05. Please revise
My answer:
z= (observation-mean)/█(standard deviation@)
z=(11.9-12)/(.05)
z=(-.1)/(.05)
z=-2
Using a standard table, you determine that the critical value is –1.645. Determine if you are able to reject the null hypothesis and explain how you reached this conclusion. (Your conclusion should include a comment relating the results to the original problem.)
Grader Comment:
When revising the explanation to reflect the corrected z-score, please reconsider where the critical (rejection) region lies. Please add a comment relating back to the original problem. What should the researcher do or not do?
My answer:
-2 is less than -1.645 so you will not reject the Ho.
Click here to see answer by stanbon(26259) |
Question 142566This question is from textbook
: Calculate the test statistic and p-value for each sample.
a. H0: μ = 60 versus H1: μ = 60, α = .025, ¯x = 63, σ = 8, n = 16
b. H0: μ ≥ 60 versus H1: μ < 60, α = .05, ¯x = 58, σ = 5, n = 25
c. H0: μ ≤ 60 versus H1: μ > 60, α = .05, ¯x = 65, σ = 8, n = 36This question is from textbook
Click here to see answer by stanbon(26259) |
Question 142794: Suppose three coins are tossed find each probability. Please do all
1.)P( exactly 1 tail)
2.)P(exactly 2 heads)
3.)P(3 tails)
4.)P(all the same)
5.)P(1 or more tails)
6.)P(3 heads)
Please help me thanks!!!
P.S Please do all
Click here to see answer by stanbon(26259) |
Question 142919: In this problem set we are asked to answer a series of 5 questions that pertain to the probability that the local hardware/sporting goods store in Dove Creek, Montana will gross over $850.00. In the space below we will discuss each question in detail. Before we can begin our exploration we must first answer some key questions that will help us to reach the proper conclusions. State what makes the trial, (which in our study is days the store grossed over $850.00), what is a success, (which in our study will be days the store grossed more than $850.00), what is a failure, (which in our study is days when the store did not make more than $850.00), and finally to give the values of the following:
n = will vary for each set but will be the following number of Business days for each:
n = 5 business days for 8a
n = 10 business days for 8b and 8c
n = 20 business days for 8d and 8e
p = .60%
q = 0.40%, because q = 1 – p or q = 1 – 0.60% = 0.40%
Armed with this we are then going to answer the 5 main questions as follows:
8a at least 3 out of 5 business days
To solve for this we will use the inequality found on page 224 as follows:
P (r ≥ 3)
Let’s begin by using the technique found on page 222 part b as follows:
P (r ≥ 3) = P (r = 3or r = 4 or r = 5)
Now that we are armed with the proper technique we will use table 2 in the appendix and a calculator to solve for P (r ≥ 3). Again I will use a calculator and write the steps down for you:
P (r ≥ 3) = P (.346 + .259 + .078)
P (r ≥ 3) = .346 + .259 + .078 =
P (r ≥ 3) = 0.683 % chance that at least 3 out of 5 business days grossed over $850.00.
8b at least 6 out of 10 business days
To solve for this we will use the inequality found on page 224 as follows:
P (r ≥ 6)
Let’s begin by using the technique found on page 222 part b as follows:
P (r ≥ 6) = P (r = 6 or r = 7 or r = 8 or r = 9 or r = 10)
Now that we are armed with the proper technique we will use table 2 in the appendix and a calculator to solve for P (r ≥ 6). Again I will use a calculator and write the steps down for you:
P (r ≥ 6) = P (.251 + .215 + .121 + .040 + .006)
P (r ≥ 6) = .251 + .215 + .121 + .040 + .006 =
P (r ≥ 6) = 0.633 % chance that at least 6 out of 10 business days grossed over $850.00.
8c fewer than 5 out of 10 business days
To solve for this we will use the inequality found on page 224 as follows:
P (r < 5)
Let’s begin by using the technique found on page 222 part b as follows:
P (r < 5) = P (r = 0 or r = 1 or r = 2 or r = 3 or r = 4 or r = 5)
Now that we are armed with the proper technique we will use table 2 in the appendix and a calculator to solve for P (r < 5). Again I will use a calculator and write the steps down for you:
P (r < 5) = P (.000 + .002 + .011 + .042 + .111 + .201)
P (r < 5) = .000 + .002 + .011 + .042 + .111 + .201 =
P (r < 5) = 0.367 % chance that fewer than 5 out of 10 business days grossed over $850.00.
8d fewer than 6 out of the next 20 business days. If this actually happened, might it shake you confidence in the statement p = 0.60? Might it make you suspect that p is less than 0.60? Explain.
8e more than 17 of the next 20 business days. If this actually happened, might you suspect that p is greater than 0.60? Explain.
Click here to see answer by stanbon(26259) |
Question 142907: Find each experimental probability. Write your answer as a fraction, decimal,and a pecent.
1.) eric bowls 35 times and gets 15 strikes. Find the experimental probability that Eric will bowl a stike.
Thanks
Click here to see answer by stanbon(26259) |
Question 142915: 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 142971This question is from textbook Mathematics All Around
: Please help me understand probability and if i set up this problem correctly?
I am struggle with knowing how to lay out to get the correct answers.
This is on a hand out sheet so it is not my math book.
Indicated probability.
A box contains 20 blue marbles, 16 green marbles and 14 red marbles. Two marbles are selected at random without replacement. Let E be the event that the first marble selected is green. Let F be the event that the second marble selected is green. Find P(F/E).
First i added the total number of marbles 20+16+14 = 50
Then I put 16/50 * 15/49 = 24/25 =.96 = 96%
Would the P(16/15) = 96%?
I am not sure if this is correct.
Thank You.
This question is from textbook Mathematics All Around
Click here to see answer by oscargut(682)  |
Question 142941: Last year the records of Dairy Land Inc., a convenience store chain, showed the mean amount spent by a customer was $30. A sample of 40 transactions this month revealed the mean amount spent was $33 with a standard deviation of $12. At the 0.05 significance level, can we conclude that the mean amount spent has increased? What is the p-value? Follow the five-step hypothesis testing procedure.
Click here to see answer by stanbon(26259) |
Question 142940: A 1990 census report revealed that the mean distance that U. S. citizens live from their birthplace is 50 miles and that the standard deviation is 15 miles. A random sample of 49 residents of your city yielded a mean distance of 56 miles.
Click here to see answer by stanbon(26259) |
Question 143037: A furniture buyer has ordered 100 grandfather clocks from an overseas manufacturer. Four clocks are damaged in shipment, but the packaging shows no indication of such damage. If a dealer buys 6 clocks without examining the contents, what is the probability that she does not have a damaged clock?
Click here to see answer by stanbon(26259) |
Question 143041: Jane visits 2 doctors, Dr. Skaer and Dr. Queern, for a diagnosis. The probability that Dr. Skaer correctly diagnoses a disease is 97/100, and the probability that Dr. Queern correctly diagnosises a disease is 93/100. What is the probability that at least one of the two doctors makes the correct diagnosis?
Click here to see answer by edjones(3292)  |
Question 143172This question is from textbook
: Marty bought 5 lbs. of apples for 98 cents a pound. a week later, she bought 7 lbs. of apples for 74 cents. what was the average price per pound that marty paid for apples?This question is from textbook
Click here to see answer by jojo14344(1483) |
Question 143246: A sample of 40 observations is selected from one population. The sample mean is 102 and the sample STDEV is 5. A second sample of 50 observations is selected from a second population. That sample mean is 99 and the STDEV is 6. Conduct the following test of hypotheses using the 0.04 significance level:
H(0): m(1) = m(2)
H(1): m(1) is not equal to m(2)
a. Is this a one-tailed or a two-tailed test?
b. State the decision rule.
c. Compute the value of the z- test statistic.
d. State your decision regarding H(0).
Please answer in excell spreadsheet if possible.
Click here to see answer by stanbon(26259) |
Question 143220: Do a larger proportion of people own cats live in houses or apts?
Group 1 Houses Group 2 Apts
Number who own cats: x1= 833 x2 = 692
Number Surveyed: n1 = 850 n2 = 740
I need to perform the five step hypothesis test.
Click here to see answer by stanbon(26259) |
Question 143171This question is from textbook
: Abe, brian, and Carmela share the responsibility of caring for the family pets. during a seven day week, abe and brian each take 3 days and carmela takes the other one. in how many different orders can the days of a week be assigned?This question is from textbook
Click here to see answer by stanbon(26259) |
Question 143142: he Rocky Mountain district sales manager of Rath Publishing, Inc., a college textbook publishing company, claims that the sales representatives make an average of 40 sales calls per week on professors. Several reps say that this estimate is too low. To investigate, a random sample of 28 sales representatives reveals that the mean number of calls made last week was 42. The standard deviation of the sample is 2.1 calls. Using the 0.05 significance level, can we conclude that the mean number of calls per salesperson per week is more than 40? (Remember to complete the 5 step hypothesis testing procedure to answer this question).
Click here to see answer by stanbon(26259) |
Question 143056: If a thumbtack is dropped, the probability of its landing point up is 2/5. Mrs. Johnson drops 10 tacks whle putting up the lunch menus for the week on the bulletin board. Find the probability that at least 6 point up.
Click here to see answer by stanbon(26259) |
Question 143140: 2. A 1990 census report revealed that the mean distance that U. S. citizens live from their birthplace is 50 miles and that the standard deviation is 15 miles. A random sample of 49 residents of your city yielded a mean distance of 56 miles.
a. Set up the null and alternative hypotheses to test if the mean distance from residence to birthplace for people living in your city differs from the census report.
b. Test your hypothesis using α = 0.01.
c. Find the p value.
d. Based on the results of the study, what can you conclude?
Click here to see answer by stanbon(26259) |
Question 143139: Last year the records of Dairy Land Inc., a convenience store chain, showed the mean amount spent by a customer was $30. A sample of 40 transactions this month revealed the mean amount spent was $33 with a standard deviation of $12. At the 0.05 significance level, can we conclude that the mean amount spent has increased? What is the p-value? Follow the five-step hypothesis testing procedure.
Click here to see answer by stanbon(26259) |
Question 143327: Part 2) Exercise #2 The null and alternate hypotheses are:
H(0): m(1) = m(2)
H(1): m(1) is not equal to m(2)
A random sample of 10 observations from one sample revealed a sample mean of 23 and a sample STDEV of 4. A random sample of 8 observations from another population revealed a sample mean of 26 and a sample STDEV of 5. At the 0.05 significance level, is there a difference between the population means? Also, (a) state the decision rule, (b) compute the pooled estimate of the population variance,(c) compute the t-test statistic, (d) state your decision about the null hypothesis, and (e) estimate the p-value.
Click here to see answer by stanbon(26259) |
Question 143448: a candy jar has red and black licorice sticks. There are 12 more red licorice sticks than black. If jorge chooses one licorice stick, without looking, there is a 60% probability that it is red. How many red licorice sticks are in the candy jar?
Click here to see answer by stanbon(26259) |
Question 143683This question is from textbook Mathematics All Around
: This is in my text book and I am trying to understand and work out problems 55 and 56. I have struggled for over 3 hours now and am getting nowwhere can you help me please?
I know you have to draw the bell curve but i do not understand how and where to put the numbers etc. I am drawing a blank here. I know the rule is 68%,95%, 99.7% rule. What little step am i missing? Can you please help turn on the light bulb for me. This is not an assigned problem but i have other like it and need to know how to do them. Any help from you would be a blessing and so appreciated.
Question:
Due to random variations in the operation of an automatic coffee machine, not every cup is filled with the same amount of coffee. Assume that the mean amount of coffee dispernsed is 8 ounces and the standard deviation is 0.5 ounces. Use Figure 14.12 to solve.( Which is just a bell cure showing the 68-95-99.7 rule for normal distribution).
I know the mean is in the middle, after that i just sit here looking at it. Please help.
Problem 55. Analyzing vending machines.
a. What percentage of the cups should have at least 8 ounces of coffee?
b. What percentage of cups should have less than 7.5 ounces of coffee?
How do i draw the curve to obtain this information?
Can you please show/tell me in detail so i can understand? Thank YouThis question is from textbook Mathematics All Around
Click here to see answer by rapaljer(3620) |
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