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Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 124888: Suppose you conduct a study and find that the probability of having a baby boy is 60%. Now suppose three of your relatives are going to have babies.
a) Build a tree diagram showing all the conditional probabilities and joint probabilities associated with the sex of the three new babies.
b) What rule of probability are you using to obtain the joint probabilities and why? In order to answer the “why” part of the question you must tell me why the rule of probability you chose to use applies in this case.
c) What is the probability of having one boy and two girls in the three births?
Click here to see answer by stanbon(26259)   |
Question 124838: a box of crayons contains one crayo of each of the folloeing colors:red,orange,yellow,blue,purple,black,white,pink.
(a)what is the probability of NOT choosing a 6-letter color?
(b)what is the complement of choosing green?
Click here to see answer by stanbon(26259) |
Question 124963: 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.
Click here to see answer by stanbon(26259) |
Question 125134: A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on a very accurate scale. The results in grams were
3.087 3.131 3.241 3.241 3.270 3.353 3.400 3.411 3.437 3.477
(a) Construct a 90 percent confidence interval for the true mean weight. (b) What sample size would be necessary to estimate the true weight with an error of ± 0.03 grams with 90 percent confidence? (c) Discuss the factors which might cause variation in the weight of Tootsie Rolls during manufacture.
Click here to see answer by stanbon(26259) |
Question 125312: A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on a very accurate scale. The results in grams were
3.087 3.131 3.241 3.241 3.270 3.353 3.400 3.411 3.437 3.477
(a) Construct a 90 percent confidence interval for the true mean weight. (b) What sample size would be necessary to estimate the true weight with an error of ± 0.03 grams with 90 percent confidence? (c) Discuss the factors which might cause variation in the weight of Tootsie Rolls during manufacture.
Click here to see answer by stanbon(26259) |
Question 125696: looking for the standard deviation for these numbers.
38 45 47 47 48 50 50 52 58 62
62 63 64 68 70 72 72 72 72 74
78 79 80 80 82 84 88 90 94 99
First I add all numbers to find the mean. 2040/30=68
here is where I get lost.
I subtract the lowest number from the mean. 38-68=-30
and subtract the largest number from the mean. 99-68=31
I square them and add them together and that is where I get stuck.
(-30*-30)=900 (31*31)=961. 900+961=1861 Now am I supposed to divide by 2 or 30
I am a little confused.
Darrin
Click here to see answer by stanbon(26259) |
Question 125696: looking for the standard deviation for these numbers.
38 45 47 47 48 50 50 52 58 62
62 63 64 68 70 72 72 72 72 74
78 79 80 80 82 84 88 90 94 99
First I add all numbers to find the mean. 2040/30=68
here is where I get lost.
I subtract the lowest number from the mean. 38-68=-30
and subtract the largest number from the mean. 99-68=31
I square them and add them together and that is where I get stuck.
(-30*-30)=900 (31*31)=961. 900+961=1861 Now am I supposed to divide by 2 or 30
I am a little confused.
Darrin
Click here to see answer by solver91311(5072)  |
Question 125756This question is from textbook underatanding stats
: a survey conducted . According to the survey 37% of adults are concerned that employers are monitoring their calls. Use the binomial distribution formula to calculate the probabilty that
a) out of 5 adults, none is concerned
b) out of 5 adults all are concerned
c) out of 5 adults exactly 3 are concernedThis question is from textbook underatanding stats
Click here to see answer by stanbon(26259) |
Question 125652: A urn has 9 white balls and 11 black balls. A ball is drawn and then replaced. If you draw a white ball you win 5 cents, if you draw a black ball you lose 5 cents. You have a dollar to gamble with, your opponent has 50 cents. IF you play until one of you loses his money, what is the probability you will lose your dollar?
Click here to see answer by kev82(145) |
Question 126062: A random sample of 100 students who took a statistics exam were asked their score on the exam. The mean score on the test was 50; the standard deviation was 10. The scores are normally distributed.
A) What percent of the students scored below 30?
B) What percent scored between 30 and 55?
Click here to see answer by stanbon(26259) |
Question 126060: A local bakery determines that the probability of a customer ordering a blueberry muffin is 50%. 5 customers come into the bakery.
A. What is the probability that 3 out of the 5 order a blueberry muffin?
B. Explain why this scenario would meet the criteria of a binomial distribution.
Click here to see answer by stanbon(26259) |
Question 126127This question is from textbook Applied Statistics in Business and Economics
: I need your help please! Two other individuals and myself tried to solve this problem; however, the examples provided in this textbook are not very helpful.
Faced with rising fax costs, a firm issues 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?This question is from textbook Applied Statistics in Business and Economics
Click here to see answer by stanbon(26259) |
Question 126144This question is from textbook Applied Statistics in Business and Economics
: Help please? I greatly need it with a lack of acceptable examples that are similiar to go by.
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 hypothesis and decision rule. (b) Is this a close decision?This question is from textbook Applied Statistics in Business and Economics
Click here to see answer by stanbon(26259) |
Question 126159This question is from textbook Applied Statistics in Business and Economics
: Kindly help me in answering as well as understanding the following statistical problem.
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 the .01 level of significance, did the yellow fire trucks have a significantly lower accident rate? (a) State the hypothesis. (b) State the decision rule. (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.This question is from textbook Applied Statistics in Business and Economics
Click here to see answer by stanbon(26259) |
Question 126171This question is from textbook Applied Statistics in Business and Economics
: Please provide some assistance in solving and understanding this statistics problem. Thanks in advance for your 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 a .01 level of significance. (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?This question is from textbook Applied Statistics in Business and Economics
Click here to see answer by stanbon(26259) |
Question 126220: The Carubas have a collection of 28 video movies, including 12 westerns and 16 science fiction. Elise selects 3 of the movies at random to bring to a sleep-over at her friend's house, find the probability of:
P(3 science fiction), P(2 westerns and 1 science fiction) and P(2 science fiction and 2 westerns).
Click here to see answer by stanbon(26259) |
Question 126321: The following data is a random sample of 1st quiz scores from previous classes.
9.5, 6.5, 4.25, 8.5, 7.5, 4.5, 4.25, 6, 7
x=6.44 s = 1.89
A) Based on the above data, find a 95% confidence interval for the average score on the 1st quiz.
B) Describe what the confidence interval tells you
Click here to see answer by stanbon(26259) |
Question 126318: The following table shows gender and soda preference of 300 people sampled:
Soda Preference
Gender Diet Soda Regular Soda No Soda Totals
Male 70 40 20 130
Female 110 45 15 170
Total 180 85 35 300
A. Draw a Bayesian Tree from the data in the table.
B. Are these two variables (gender & soda preference) independent?
C. What is the probability of randomly selecting someone who is Male or prefers Regular Soda?
Click here to see answer by stanbon(26259) |
Question 126190This question is from textbook Applied Statistics in Business and Economics
: Please provide assistance in solving this problem if you can. Thank you!
In a bumper test, three types of autos were deliberately crashed into a barrier at 5mph, and the resulting damage (in dollars) was estimated. Five test vehicles of each type were crashed, with the results of the Goliath 1,600 760 880 1,950 and 1,220, the Varmint 1,290 1,400 1,390 1,850 and 950, and the Weasel 1,090 2,100 1,830 1,250 and 1,920. Are the mean crash damages the same for these three vehicles?This question is from textbook Applied Statistics in Business and Economics
Click here to see answer by stanbon(26259) |
Question 126400: I don't know what this would fall under, in my text it is under expectations in probability:
500 raffle tickets are sold at $2.00 each. One grand prize is $100.00 and two consolation prizes of $50.00 will be awarded. Find Jake's expectation if he purchases one ticket.
I set my problem up as:
Jake's expectation would be to loose $1.60
Is this the right way to set this up?
Thanks for your help!
Click here to see answer by stanbon(26259) |
Question 126418: 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 126316: Please help...thank you
The following are the first Quiz scores from a previous class:
9.5, 7.5, 9.5, 7, 10, 7.5, 6.5, 1.5, 8, 10
A. Is this data discrete or continuous and why?
B. Develop a frequency distribution showing all frequencies, cumulative frequencies, and relative frequencies.
C. Calculate the Variance and Standard Deviation and describe what they tell you in the context of this problem.
Click here to see answer by stanbon(26259) |
Question 126542: The fill amount of bottles of soft drink has been found to be normally distributed with a mean of 2.0 liters and a standard deviation of 0.05 liters. If random sample of bottles is selected, what is the probability that the sample mean will be between 1.99 and 2.0 liters:
Click here to see answer by stanbon(26259) |
Question 126646This question is from textbook Apllied Statics
: Please give guidance to this question from the Text Book Chapter 9 9.62. Thank you. 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 precessed on the same day, would this prove that they are exceeding their goal, using a=.025?This question is from textbook Apllied Statics
Click here to see answer by stanbon(26259) |
Question 126661This question is from textbook Elementary Statistics
: A study of 420,095 Danish cell phone users found that 135 of them developed cancer of the brain or nervous system. Prior to this study of cell phone use, the rate of such cancer was found to be 0.0340% for those not using cell phones. The data are from the Journal of the National Cancer Institute.
a. Use the sample data to construct a 95% confidence interval estimate of the percentage of cell phone users who develop cancer of the brain or nervous system.
This question is from textbook Elementary Statistics
Click here to see answer by stanbon(26259) |
Question 126658This question is from textbook Elementary Statistics
: In a survey of 1002 people, 701 said that they voted in a recent presidental election (based on data from ICR Research Group). Voting records show that 61% of eligible voters actually did vote.
a. Find a 99% confidence interval estimate of the proportion of people who say that they voted.
b. Are the results consistent with the actual voter turnout of 61% why or why not?This question is from textbook Elementary Statistics
Click here to see answer by stanbon(26259) |
Question 126741: The probability 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 U.S. driver takes 50,000 trips. (a) What is the probability 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”?
Click here to see answer by MathLover1(1183)  |
Question 126188This question is from textbook Applied Statistics in Business and Economics
: I need help some help in solving this problem, please?
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 the .05 level of significance, is there a difference in variances? Show all steps clearly, including an illustration of the decision rule.This question is from textbook Applied Statistics in Business and Economics
Click here to see answer by stanbon(26259) |
Question 126177This question is from textbook Applied Statistics in Business and Economics
: Please provide assistance for the following problem/questions. Thanks!
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 the .05 level of significance? (a) State the hypotheses for a right-tailed test. (b) Obtain a test statistic and p-value assuming equal variances. Interpret the 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 the .05 level of significance, showing all steps clearly.This question is from textbook Applied Statistics in Business and Economics
Click here to see answer by stanbon(26259) |
Question 126754: Textbook Question from Applied Statistics in Business and Economics, by Doane and Seward
To test the hypothesis that students who finish an exam first get better grades, Professor Hardtrack kept track of the order in which papers were handed in. The first 25 papers showed a mean score of 69.3 with a standard deviation of 24.9. Is this a significant difference at ? (a) State the hypothesis for a right-tailed test. (b) Obtain a test statistic and p-value assuming equal variances? (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 , showing all steps clearly.
Click here to see answer by stanbon(26259) |
Question 126791: PlEASE help!
Raffle tickets.
One thousand raffle tickets are sold for $1 each. One prize of $800 is to be awarded.
a) Rena Condos purchases one ticket. Find her expected value.
b) Determine the fair price of a ticket.
Click here to see answer by stanbon(26259) |
Question 126804:
PlEASE help!
Raffle tickets.
One thousand raffle tickets are sold for $1 each. One prize of $800 is to be awarded.
a) Rena Condos purchases one ticket. Find her expected value.
b) Determine the fair price of a ticket.
Click here to see answer by stanbon(26259) |
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