Tutors Answer Your Questions about Probability-and-statistics (FREE)
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(2920)   |
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(26259) |
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(3382)  |
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(13787) |
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(13787) |
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(26259) |
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(26259) |
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(26259) |
Question 149583: Please help. I have to solve this multiple-choice problem, but I have no idea how to begin. I have asked this before, but the response was not one of four possibilities, and I could not work it by the solver's explanation.
Here is the problem: A lottery has one $2000, prize, two $1000. prizes, and ten $500. prizes. Two thousand tickets are sold at $5 each. Find the expectation if a person buys two tickets.
My possible answers are: 1) -$0.50 2) -$1.00 3) -2.00 4) -$0.25. I am pulling my hair out on this one.
Ellen
Click here to see answer by tennisbuff07(20) |
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(3382) |
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(26259) |
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(26259) |
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(26259) |
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(26259) |
Question 150223: Please help,
The average hourly wage of employees of a certain company is $9.83. Assume the variable is normally distributed. If the standard deviation is $4.58, find the probability that a randomly selected employees earns less than $5.43.
Please help,
Ellen
Click here to see answer by stanbon(26259) |
Question 150495: A study conducted by the research department of a pharmaceutical company claims that the annual spending (per person) for prescription drugs for allergy relief, m1 , is greater than or equal to the annual spending (per person) for non-prescription allergy relief medicine, m2 . A health insurance company conducted an independent study and collected data from a random sample of 255 individuals for prescription allergy relief medicine. The sample mean is found to be 17.8 dollars/year, with a sample standard deviation of 5.1 dollars/year. They have also collected data for non-prescription allergy relief medicine. An independent random sample of 245 individuals yielded a sample mean of 18.2 dollars/year, and a sample standard deviation of 4.3 dollars/year. Since the sample size is quite large, it is assumed that the population standard deviation of the sales (per person) for prescription and non-prescription allergy relief medicine can be estimated by using the sample standard deviation values given above. Is there sufficient evidence to reject the claim made by the research department of the company, at the 0.10 level of significance?
Perform a one-tailed test and answer the questions below.
Carry your intermediate computations to at least three decimal places and round your answers to three as well.
1) The null hypothesis
2) The alternative hypothesis
3) The type of test statistic (ex. Z, t, Chi-Square, etc.)
4) The value of the test statistic
5) The p value
6) YES or NO. Can we reject the claim that the mean spending on prescription allergy relief medication is greater than or equal to the mean spending on non-precription allergt relief medication?
Click here to see answer by stanbon(26259) |
Question 150513: The General Social Survey is an annual survey given to about 1,500 U.S. adults selected at random. Each year, the survey contains several questions meant to probe respondents' views of employment. A recent survey contained the question "How important to your life is having a fulfilling job?" Of the 261 college graduates surveyed, 107 chose the response "Very important." Of the 121 people surveyed whose highest level of education was high school or less, 34 chose the response "Very important." Based on these data, can we conclude, at the 0.05 level of significance, that there is a difference between the proportion p1 of all U.S. college graduates who would answer "Very important" and the proportion p2 of all U.S. adults whose highest level of education was high school or less who would answer "Very important"?
Perform a two-tailed test. Then answer the 6 questions below.
Carry your intermediate computations to at least three decimal places and round your answers the same way.
1) The null hypothesis
2) The alternative hypothesis
3) The type of test statistic (Z, t, chi-square, etc)
4) The value of the test statistic
5) The p-value
6) (YES OR NO) Can we conclude that there is a difference between the two populations in the proportions who would answer "very important"?
Click here to see answer by stanbon(26259) |
Question 150654: A manufacturer wants to increase the absorption capacity of a sponge. Based on past data, the average sponge could absorb 3.5 ounces. After the redesign, the absorption amounts of a sample of sponges were (in ounces): 4.1, 3.7, 3.3, 3.5, 3.8, 3.9, 3.6, 3.8, 4.0, and 3.9. What is the decision rule at the 0.01 level of significance to test if the new design increased the absorption amount of the sponge?
Click here to see answer by stanbon(26259) |
Question 150762: At school festival, a colored chip is randomly drawn out of a bag,and replaced. The tabel Below shows the results of 50 draws. Estimate the probability of choosing a purple chip.
Outcome|Blue|Red|Green|Purple|Gold
Draws | 7 | 11| 8 | 12 | 14
A. 12% B. 18% C. 24% D. 88%
Click here to see answer by mangopeeler07(450) |
Question 150649: From past records it is known that the average life of a battery used in a digital clock is 305 days. The battery life is normally distributed. The battery was recently modified to last longer. A sample of 20 of the modified batteries was tested. It was discovered that the mean life was 311 days and the sample standard deviation was 12 days. We want to test at the 0.05 level of significance whether the modification increases the life of the battery. What is our decision rule?
Click here to see answer by stanbon(26259) |
Question 146423: A certain airplane has two independent alternators to provide electrical power. The probability that a given alternator will fail on a 1-hour flight is .02. What is that (a) both will fail (b) Neither will fail? (c) One or the other will fail? Show all steps carefully?
Click here to see answer by nickstud(1) |
Question 151265This question is from textbook
: 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?
Crash 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 This question is from textbook
Click here to see answer by mducky2(55) |
Question 151215: One overnight case contains 2 bottles of aspirin and 3 bottles of thyroid tablets. A second tote bag contains 3 bottles of aspirin, 2 bottles of thyroid and 1 bottle of laxative tablets. If 1 bottle is taken at random from each piece of luggage, find the probability that
a. both bottles contain thyroid tablets
b. neither bottle contains thyroid tablets
c. the 2 bottles contain different tablets
Click here to see answer by edjones(3292)  |
Question 151221: I am trying to determine if I am going the right direction, more so than wanting someone just to answer the question. Here is the question;
Define “association” in statistics. Explain how association is identified and demonstrated.
My answer –
Association is a commonality between two variables demonstrated by a shared value. Association is often indentified mathematically by plotting variables on a graph, when variables share a point it can be said they are associated. Association can also be demonstrated through plotting. Real world association can be defined when two variables share a common factor. Such as January and snow, they are associated because they both occur during the same time of year but one does not cause the other.
Am I heading the right way with this?
Click here to see answer by nabla(412) |
Question 151420: the incubation time for rhode island red chicks is normally distributed with a mean of 21 days and standard deviation of approx. 1 day look at figure 7-3 and answer the following questions. if 1000 eggs are being incubated how many chicks do we expect will hatch
a) in 19 to 23 days
b) in 20 to 22 days
c) in 21 days or fewer
d)in 18 to 24 days? ( assume all eggs eventually hatch)
Click here to see answer by stanbon(26259) |
Question 151425: Please help me understand this can you please show me how you get your answers so i can understand it.
A vending machine automatically pours soft drinks into cups. The amount of soft drink dispensed into a cup is normally distributed with a mean of 7.6oz and standard deviation of 0.4oz. Examine figure 7.- and answer the following questions.
a) estimate the probability that the machine will overflow an 8oz cup.
b) Estimate the probabiltiy that the machine will not overflow an 8oz cup.
c) the machine has just been loaded with 850 cups. HOw many of these do you expect will overflow when served?
Please can you help me understand this
Click here to see answer by stanbon(26259) |
Question 152038: A building supervisor measured the time it took in days for two builders to build the same
houses under similar conditions. Both builders had the same mean of 190 days, but the
standard deviation for builder A was 21 days, while for builder B it was 12 days.
On the basis of this data, which builder is most likely to finish a house:
a in the shortest time?
b in the longest time?
c closest to 190 days?
Click here to see answer by vleith(1977) |
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