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Tutors Answer Your Questions about Probability-and-statistics (FREE)

Question 358279: A recent study reports that 2.5% of elementary children are allergic to peanuts. A random sample of 200 elementary school children is collected to test this.

Compute the probability that proportion of children in the sample of 200 who are allergic to peanuts is 3% or less. ( < .03).
Click here to see answer by stanbon(57219)

Question 358274: The marketing department of a nationally known cereal maker plans to conduct a national survey to find out whether or not consumers of flake cereals can distinguish one of their favorite flake cereals. To test the questionnaire and procedure to be used, eight persons were asked to cooperate in an experiment. Five very small bowls of flake cereals were placed in front of a person. The bowls were labeled A, B, C, D and E. The person was informed that only one bowl contained his or her favorite flake cereal. Suppose that the eight persons in the experiment were unable to identify their favorite cereal and just guessed which bowl it was in. What is the probability that none of the eight guessed correctly?

Click here to see answer by Edwin McCravy(8880)

Question 358276: The fuel economy of a particular car model is normally distributed with a mean of 25 mpg and a standard deviation of 1.25 mpg. A random sample of 10 cars is selected.

Compute the standard error, standard deviation of the mean , for the sample of 10 cars.
Click here to see answer by stanbon(57219)

Question 358400: A bag contains 5 red marbles, 6 green marbles, and 9 blue marbles. Suppose 3 marbles are chosen without replacement. What is the probability of choosing a red, a blue, and a red in that order?:
Click here to see answer by robertb(4012)

Question 358426: Discipline | Male | Female | Total
--------------------------------------…
Mathematics | 6 | 4 | 10 |
--------------------------------------…
Science | 5 | 2 | 7 |
--------------------------------------…
Engineering | 1 | 0 | 1 |
--------------------------------------…
Total | 12 | 6 | 18 |
--------------------------------------…
If four faculty members are randomly chosen, what is the probability that you choose four men or four mathematics instructors?
Click here to see answer by Jk22(389)

Question 358430: There are 9 men for every 10 women at the university. The total students are 26,239 how many are women?
Click here to see answer by jsmallt9(3296)

Question 358361: How do I solve this problem?
Suppose that the time required to complete a 1040R tax form is normally distributed with a mean of 90 minutes and a standard deviation of 20 minutes. What proportion of 1040R tax forms will be completed in at least 119 minutes: Round your answer to at least four decimal places.
Click here to see answer by stanbon(57219)

Question 358469: If 60% of people purchase light beer, what is the probability that 2 people will purchase light beer?
Click here to see answer by Fombitz(13828)

Question 358602: Suppose the amount of time it takes a popcorn kernel to pop is normally distributed with a mean of 150 seconds and a standard deviation of 15 seconds. If a popcorn kernal is randomly selected, what is the probability that it takes between 130 seconds to 170 seconds for the kernal to pop?
Click here to see answer by Fombitz(13828)

Question 358596: 9.47
The waiting time to place an order at a branch of a fast-food chain during the lunch hour has had a population mean of 3.55 minutes, with a population standard deviation of 1.1 minutes. Recently, in an effort to reduce the waiting time, the branch has experimented with a system in which there is a single waiting line. A sample of 100 customers during a recent lunch hour was selected, and their mean waiting time to place an order was 3.18 minutes. Assume that that the population standard deviation of the waiting time has not changed from 1.1 minutes.
a. At the level of significance, using the critical value approach to the hypothesis testing, is there evidence that the population mean waiting time to place an order is less than 3.55 minutes?
b. At the level of significance, using the p-value approach to the hypothesis testing, is there evidence that the population mean waiting time to place an order is less than 3.55 minutes?
c. Interpret the meaning of the p-value in this position.
d. Compare your conclusions in a and b.
Click here to see answer by jrfrunner(365)

Question 358655: Suppose you have a mutliple choice exam with 16 multiple choice questions. Each question has four alternatives . What is the probability that a student who guesses at random on each of the 16 questions will score 4 or lower correct answers?
Click here to see answer by stanbon(57219)

Question 358761: The access code to a house's security system consists of seven digits. How many different codes are available if each digit can be repeated?
Click here to see answer by edjones(7569)

Question 358806: 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?
Click here to see answer by edjones(7569)

Question 358847: The linear correlation coefficient is a numerical value that ranges from -1.00 to +1.00. Describe in a sentence or two the meaning of each of these correlation coefficients:
a.) -.50
b.) +1.10

Click here to see answer by stanbon(57219)

Question 358711: Drawing 3 cards from a suit of 13 cards,
1 a) probability that all three cards are not face cards without replacement
b) probability that all three cards are not face cards with replacement
Draw 3 cards from a deck of 52 cards,
2 a) probability of all three cards being red without replacement
b) probability of all three cards being red with replacement.
please show me the calculations. My teacher said I got them wrong but I don't know why.
Click here to see answer by stanbon(57219)

Question 358869: Find the first and third quartiles and the interquartile range for this sample. 730 670 610 520 690 650 600 570
Click here to see answer by neatmath(300)

Question 358939: How many ways can an IRS auditor select 6 of 12 tax returns for an audit?
Click here to see answer by nyc_function(2733)

Question 358944: A die wirh 12 sides is rolled. What is the probability of rolling a number less than 11?
Click here to see answer by solver91311(16868)

Question 358945: A sample of 4 diffrent calculators is randomly selected from a group containing 18 that are defective and 39 that have no defects. What is the probability that at least one of the calculators is defective?
Click here to see answer by solver91311(16868)

Question 358947: probability of getting the first true or false question right out of twenty questions.
probability of getting the fifth question right out of twenty.
Click here to see answer by solver91311(16868)

Question 358978: I'm not sure if this is the right section, but this question is about the normal distribution:
Tony is training for the athletic sports. He has found that 70% of the times he records are less than 56.3 seconds and 20% are less than 52.3 seconds. If the times he records are normally distributed then what are mean and the standard deviation of his times?
Thanks in advance.
Click here to see answer by robertb(4012)

Question 358941: A muscian plans to perform 10 selections. In how many ways can she arrange the musical selections?
Click here to see answer by robertb(4012)

Question 358942: Based on meteorological records, the probability that it will snow in a certain town on January 1st is 0.245. Find the probability that in a given year it will not snow on January 1st in that town.
Click here to see answer by robertb(4012)

Question 359003: Find the mean and standard deviation of the following probability distribution:
x 1 2 3
P(x)
0.1
0.2
0.7

Please show all of your work.

Click here to see answer by robertb(4012)

Question 359009: A bag of colored blocks contains the following assortment of colors:
red (9), blue (16), orange (10), purple (16), green (7), and yellow (22).

Construct the probability distribution for x.

Click here to see answer by Fombitz(13828)

Question 359007: Suppose we want to determine the (binomial) probability(p) of getting 5 heads in 14 flips of a 2-sided coin. Using the Binomial Probabilities Table in Appendix B of the text, what values of n, x and p would we use to look up this probability, and what would be the probability?

Click here to see answer by ewatrrr(10682)

Question 359027: Could someone explain this to me because the book was no help.

The random variable x has the following probability distribution:
x 1 2 3 4 5
___________________________________________________
P(x) 0.6 0.1 0.1 0.1 0.1
a.) Find the mean and standard deviation of x.
b). What is the probability that x is between mean - standard deviation and mean + standard deviation?

Click here to see answer by Fombitz(13828)

Question 359044: compute the mean, mode, range, standard deviation and variance from the following set of scores: 145, 210, 300, 178, 110, 237, 155, 187, 204, 205, 205, 287, 256, 200
Click here to see answer by Fombitz(13828)

Question 359064: A population of scores has a mean of 42.In this population, and X value of 40 corresponds to a z = -0.50. What is the population standard deviation?

Click here to see answer by Fombitz(13828)

Question 359101: In a batch of a hundred light bulbs there are 5 bad bulbs. Inspectors inspects 10 at random. Compute probability of finding at least one defective light bulb
Click here to see answer by Fombitz(13828)

Question 359141: Draw a vertical line through a normal distribution for each of the following z-score locations. Determine whether the body is on the right or left side of the line and find the proportion in the tail.
a. Z = 2.00
b. z= -1.30
c. z= 0.60
d. z= -0.30
Click here to see answer by Fombitz(13828)

Question 358870: Find the coefficient of x^5 in (1+x)^12.
Click here to see answer by Fombitz(13828)

Question 359201: A sample of 4 different calculators is randomly selected from a group containing 17 that are defective and 36 that have no defects. what is the probability that atleast one of the calculators is defective?
Click here to see answer by Fombitz(13828)

Question 359221: Suppose there is a 36% chance that a risky stock investment will end up in a total loss of your investment. Because the rewards are so high, you decide to invest in three independent risky stocks. Find the probability that at least one of your three investments becomes a total loss?
Click here to see answer by stanbon(57219)

Question 359163: Families USA, a monthly magazine that discusses issues related to health and health costs, surveyed 20 of its subscribers. It found that the annual health insurance premiums for a family with coverage through an employer averaged $10,979. The standard deviation of the sample was $1,000.
a. Based on this sample information, develop a 90 percent confidence interval for the
population mean yearly premium.
b. How large a sample is needed to find the population mean within $250 at 99 percent
confidence?

Click here to see answer by stanbon(57219)

Question 359252: Mock Questions for Class Test 1
An investment account offers an interest rate of 6% per annum compounded half yearly. Assuming a single deposit of money is placed in this investment account:
i) How much money must be invested now in order for the account to contain £45000 after 5 years?
ii) What would be the final amount of investment if £29000 is invested for 7 years?
iii) How long would it take for £29000 to amount to £68000, assuming that £1000 is withdrawn at the end of first year and thereafter no further withdrawals are made?
(£33484, £43865, 15 years)
A firm annual fixed cost of production is £7200. The annual variable costs of the production are £60 per unit of output plus £2 per square unit of output. The product is sold at a constant price of £320 per unit. Calculate the breakeven levels of production.
(40 or 90)
A man wishes to repay a debt of £4,000 by paying a fixed sum of £80 per month to reduce the debt, together with a payment of 1% interest for that month indebtedness. Make out a schedule of repayment and Find the total amount of interest paid until the debt is completely discharged.
(£1020)
In a large group of invoices, 30% had a value greater than £50. A random sample of 3 invoices was taken determine the probability that:
(i) All of the three invoices had an invoice value greater £50.
(ii) At least 2 had an invoice value greater than £50.
(iii) None of the three invoices had an invoice value greater than £50.
(0.027, 0.216, 0.343)

Click here to see answer by rfer(12644)

Question 359556: Determine whether each of the distributions given below represents a probability distribution. Justify your answer.

x
1
2
3
4

P(x)
1/12
5/12
1/3
1/12

(A)

x
3
6
8

P(x)
2/10
.5
1/5

(B)
x
20
35
40
50

P(x)
0.4
-0.2
0.5
0.3

(C)

Click here to see answer by Fombitz(13828)

Question 359599: If a point is randomly chosen on the square shown, what is the probability that it will be in a yellow section of the figure?
Click here to see answer by Fombitz(13828)

Question 359609: An automotive repair shop has determined that the average service time on an automobile is 130 minutes with a standard deviation of 26 minutes. A random sample of 40 automotive services is selected.

a. Compute the standard error of the mean.
b. What is the probability that the sample of 40 automotive services will have a mean service time greater than 136 minutes?
c. Assume the population consists of 400 automotive services. Determine the standard error of the mean.

Click here to see answer by stanbon(57219)

Question 359460: Data shows that 90% of the people in a certain population are right-handed. A group of 8 people from this population are selected at random. What is the probability that exactly 6 of the people in the group are right-handed? and What is the probability that at least 6 of the people in the group are right-handed?
Click here to see answer by Fombitz(13828)

Question 359643: I am trying to understand the probability notation. I can do the math and figure the answer, but can't get the probability notation right.
Questions is: During the winter months I have two cars that are hard to start. 1990 mustang and a 1993 ranger. The probability that my mustang will start is .08 and the ranger is .03. Let A represent the mustang starts, and B represent the ranger starts event. Use the probability notation and solve the following.
A. What is the possibility that I can start at least one car?
B. What is the probability that I cannot start either car?
Thanks,
Brian
Click here to see answer by stanbon(57219)

Question 359634: Classify the following as discrete or continuous random variables.

(A) The number of people in India
(B) The time it takes to overhaul an engine
(C) The weight of a school bus containing 22 football players
(D) The length of a centipede

Click here to see answer by Edwin McCravy(8880)

Question 359637: According to the college registrar's office, 60% of students enrolled in an introductory statistics class this semester are freshmen, 25% are sophomores, 10% are juniors, and 5% are seniors. You want to determine the probability that, in a random sample of five students enrolled in introductory statistics this semester, exactly two are freshmen.
Click here to see answer by stanbon(57219)

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