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Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 129787: thank you for your answers to question 129775 but I did a,b,and c on my own and did not come up with your answers so could you please take me step by step through the process, because I am missing something.
Click here to see answer by oscargut(682)   |
Question 129780: Please,I really need some help with this problem:
The manufacturer of Winston Tire Company (WTC) claims its new tires last for an average 45k miles. An independent testing agency road-tested 135 tires to substantiate the claim made by WTC. The sample mean was 44k miles with a sample standard deviation of 4k miles. Using 1% significance, determine if there is a reason to reject the claim made by WTC and conclude that the tires last for less than 45k miles.
Lets do this in an interactive fashion.
First, answer the following questions:
- what is 'n'
- calculate the confidence intervals (using 44k miles as your mean) (1% significance means 99% confidence)
Thanks...
Click here to see answer by stanbon(26259)  |
Question 129839: How tall are college hockey players? The average height has been 68.3 inches. A random sample of 14 hockey players gave a mean height of 69.1 inches. We may assume that x has a normal distribution with σ = 0.9 inch. Does this indicate that the population mean height is different from 68.3 inches? Use 5% level of significance.
a) State the null and the alternate hypothesis.
b) Identify the sampling distribution to be used: the standard normal distribution or the Student's t distribution. Find the critical value(s).
c) Compute the z or t value of the sample test statistic.
d) Find the P value or an interval containing the P value for the sample test statistic.
e) Based on your answers to a through d, decide whether or not to reject the null hypothesis at the given significance level. Explain your conclusion in the context of the problem.
Click here to see answer by stanbon(26259) |
Question 129837: Roger has read a report that the weights of adult mail Siberian tigers have a distribution which is approximately normal with mean μ = 390 lb and σ = 65 lb.
a) Find the probability that an individual male Siberian tiger will weigh more than 450 lb.
b Find the probability that a random sample of 4 male Siberian tigers will have a sample mean weight more than 450 lb.
Click here to see answer by stanbon(26259) |
Question 129836: Researchers at a pharmaceutical company have found that the effective time duration of a safe dosage of a pain relief drug is normally distributed with mean 2 hours and standard deviation 0.3 hour. For a patient selected at random:
a) What is the probability that the drug will be effective for 2 hours or less?
b) What is the probability that the drug will be effective for 1 hour or less?
c) What is the probability that the drug will be effective for 3 hours or more?
Click here to see answer by stanbon(26259) |
Question 129892This question is from textbook Applied Statistics in Business and Economics
: I need your help ASAP, Thank you!!
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 α = .05, 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 129826: Let x be a random variable that represents the length of time it takes a student to write a term paper for Dr. Adam's Sociology class. After interviewing many students, it was found that x has an approximately normal distribution with mean μ = 6.8 hours and standard deviation σ = 2.1 hours.
Convert each of the following x intervals to standardized z intervals:
a) x ≤ 7.5
b) 5 ≤ x ≤ 8
c) x ≥ 4
Convert each of the following z intervals to raw score x intervals:
d) z ≥ -2
e) 0 ≤ z ≤ 2
f) z ≤ 3
Click here to see answer by stanbon(26259) |
Question 129973: I already submitted this question. The missing data is Apha=.05. Please help me. I am totally lost and need your help. Thank you again
1. The EPA is concerned about the quality of drinking water served on airline flights. A sample of 158 flights yielded poor quality water on 20 flights. At alpha=.05, does this indicate that more than 10% of flights have poor-quality water?
2. According to the sample, 12.66% (20/158) of the flights served poor-quality water. Can you simply report to the EPA that more than 10% of all airline flights serve poor-quality water? Why or why not?
3. If an error occurred, what type of error was it?
Click here to see answer by stanbon(26259) |
Question 129930: Let x be a random variable that represents the length of time it takes a student to write a term paper for Dr. Adam's Sociology class. After interviewing many students, it was found that x has an approximately normal distribution with mean μ = 6.8 hours and standard deviation σ = 2.1 hours.
Convert each of the following x intervals to standardized z intervals:
a) x ≤ 7.5
b) 5 ≤ x ≤ 8
c) x ≥ 4
Convert each of the following z intervals to raw score x intervals:
d) z ≥ -2
e) 0 ≤ z ≤ 2
f) z ≤ 3
Click here to see answer by stanbon(26259) |
Question 129929: Recently the national average yield on municipal bonds has been μ = 4.19%. A random sample of 16 Arizona municipal bonds gave an average yield of 5.11% with a sample standard deviation s = 1.15%. Does this indicate that the population mean yield for all Arizona municipal bonds is greater than the national average? Use α = 0.05. Assume x is normally distributed.
a) State the null and the alternate hypothesis.
b) Identify the sampling distribution to be used: the standard normal distribution or the Student's t distribution. Find the critical value(s).
c) Compute the z or t value of the sample test statistic.
d) Find the P value or an interval containing the P value for the sample test statistic.
e) Based on your answers to a through d, decide whether or not to reject the null hypothesis at the given significance level. Explain your conclusion in the context of the problem.
Click here to see answer by stanbon(26259) |
Question 130021: This is not in a textbook - Can you please help??
Let us assume that average gas prices per gallon of unleaded gasoline in U.S. are normally distributed with the mean of $2.89 and the standard deviation of $0.05. Your neighborhood gas station charges $3.13 per gallon. You suspect the station owner charges too much and wish to determine whether there is a statistically significant difference between his price and the national average. Perform the z-test of hypothesis on the 0.05 level of significance. What is the conclusion?
Click here to see answer by stanbon(26259) |
Question 129757: Please help me. I need desperate help.
1. The EPA is concerned about the quality of drinking water served on airline flights. A sample of 158 flights yielded poor quality water on 20 flights. At =.05, does this indicate that more than 10% of flights have poor-quality water?
2. According to the sample, 12.66% (20/158) of the flights served poor-quality water. Can you simply report to the EPA that more than 10% of all airline flights serve poor-quality water? Why or why not?
3. If an error occurred, what type of error was it?
Click here to see answer by stanbon(26259) |
Question 130143: question 1
According to a survey, 50% of employees in banking sector are satisfied with their jobs. Assume this is the true proportion of all satisfied employees in banking sector. Let p be the proportion of banking sector employees in a random sample of 1000 who are satisfied with their jobs.
a) Describe the shape of the sampling distribution for the sample proportion.
b) Find the mean and standard deviation of the sample proportion, p.
questions 2
Assume that the weights of all mini-packages of a certain brand biscuits are normally distributed with mean of 32 grams and standard deviation of 0.3 grams. Find the probability that the mean weightx, of a random sample of 20 packages of this brand of biscuits will be between 31.8 and 31.9 grams.
Click here to see answer by stanbon(26259) |
Question 130135: Debra is buying prizes for a game at her school’s fundraiser. The game has three levels of prizes (and some players will lose), and she has already bought the second and third prizes. She wants the first prize to be nice enough to attract people to the game. The game’s manufacturer has supplied her with the probabilities of winning first, second and third prizes. Tickets cost $3 each, and she wants the school to profit an average of $1 per ticket. How much should she spend on each first prize?
Prize Cost of Prize Probability
1st ? 0.15
2nd $1.25 0.30
3rd $0.75 0.45
Click here to see answer by stanbon(26259) |
Question 130159: A certain airplane has two independent alternators to provide electrical power. The probability that a given alternator will fall on a 1-hour flight is .02. What is the probability that (a) both will fail? (b) Neither will fail? (c) One or the other will fail?
Click here to see answer by edjones(3292)  |
Question 130146This question is from textbook cpm algerbra
: a box contains 24 red cubes and x blue cubes. the probibility of pulling out a blue is 1/3.
a. how many cubes are there all together?
b.write an expression from part (a)for the probibilty of pulling out a blue cube.
c.write and solve an equation with two equal ratios to find the number of blue cubes
d.explain why your anwer makes senseThis question is from textbook cpm algerbra
Click here to see answer by edjones(3292) |
Question 130158: Hi,
Not sure if this is correct, but is the answer 52,000? I am thinking that the problem should be set up as follows:
650,000 x 4% for two years...therefore 650,000x8%????
Question:
If 650,000 is invested in an account paying simple annual interest, how much interest will be earned in two years at the annual rate of 4%?
Click here to see answer by bucky(1732) |
Question 130165: QUESTION 1
a) How much is the total amount after 3 years of investment if RM5000 was invested at the
interest rate of 2% per annum, compounded every half a year?
b) Find the annual interest rate if the total amount after 5 years of investment is RM248,832
where the principal amount was RM100,000 and compounded annually.
Question 2
Using product and quotient rule, find the differentiation for f(x):
f(x)=x^2+2x/x^2-4
Question 3
Using the chain rule, find dy/dx when y=(3-x^-3)^2
Click here to see answer by stanbon(26259) |
Question 130275: Help me please! 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 assumptions. (c) Would the quick rule apply here?
I don't have an ISBN number because it's an online course through UOP.
Click here to see answer by stanbon(26259) |
Question 130218: Identify the sampling technique used to obtain a sample. Explain your answer.
The businessess in Iowa City are grouped according to type: medical, service, retail, manufacturing ,financial,construction,restaurant,hotel,toursim,and other. A random sample of 10 businessess from each type is selected.
Click here to see answer by stanbon(26259) |
Question 130388: The daily double at most race tracks consists of selecting the winning horse in both the first and second races. If the first race has 8 entries and the second race has 9 entries, how many daily double tickets must be purchased to guarantee a win?
Click here to see answer by checkley71(8405) |
Question 130429This question is from textbook Statistics
: A 35 year old woman purchases a $100,000 term life insurance policy for an annual payment of $360. Based on a period life toable for the U.S. government, the probablity that she will survive the year is is 0.999057. Find the expected value of the policy for the insurance company.This question is from textbook Statistics
Click here to see answer by checkley71(8405) |
Question 130426This question is from textbook Statistics
: An insurance company insures a person's antique collection worth $20,000 for an anuual premium of $300.00. If the company figures that the probablity of the collection being stolen is 0.002, what will be the company's expected profit?
I have no clue on how to do this...please helpThis question is from textbook Statistics
Click here to see answer by scott8148(3382)  |
Question 130409: 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 hypotheses and decision rule. (b) Is this a close decision?
Click here to see answer by stanbon(26259) |
Question 130452: Please kindly help me. I don't know how to do this question.
High levels of cockpit noise in an aircraft can damage the hearing of pilots who are exposed to this hazard for many hours. A Boeing 727 co-pilot collected 61 noise observations using a handheld sound meter. Noise level is defined as “Low” (under 88 decibels), “Medium” (88 to 91 decibels), or “High” (92 decibels or more). There are three flight phases (Climb, Cruise, Descent). Research question: At α = .05, is the cockpit noise level independent of flight phase?
Noise Level Climb Cruise Descent Row Total
Low 6 2 6 14
Medium 18 3 8 29
High 1 3 14 18
Col Total 25 8 28 61
Click here to see answer by stanbon(26259) |
Question 130451: Please help me. I am stuck with this question.
A student team examined parked cars in four different suburban shopping malls. One hundred vehicles were examined in each location. Research question: At α = .05, does vehicle type vary by mall location?
Vehicle Type Somerset Oakland Great Lakes Jamestown Row Total
Car 44 49 36 64 193
Minivan 21 15 18 13 67
Full-sized Van 2 3 3 2 10
SUV 19 27 26 12 84
Truck 14 6 17 9 46
Col Total 100 100 100 100 400
Click here to see answer by stanbon(26259) |
Question 130385: The owner of a stereo store wants to advertise that he has many different sound systems in stock. The store carries 6 different CD players, 9 different recievers, and 8 different speakers.
Assuming a sound system consists of one of each, how many different sound systems can he advertise?
Click here to see answer by stanbon(26259) |
Question 130530: hellppppp!!!!!
mel's light went out. she has 3 pairs of red socks in her drawer, 2 pairs of black socks and 5 pairs of white socks. what is the maximum number of pairs she can remove from the drawer to ensure she has a pair of each color?
thanksssssssss
Click here to see answer by edjones(3292) |
Question 130586: The daily double at most race tracks consists of selecting the winning horse in both the first and second races. If the first race has 8 entries and the second race has 9 entries, how many daily double tickets must be purchased to guarantee a win?
Click here to see answer by checkley71(8405) |
Question 130585: Mr. and Mrs. J. B. Davis just moved into a new home and need to purchase kitchen appliances. The Davises are going to purchase a refrigerator, a stove, and a dishwasher. They have a number of choices for each appliance.
For Refrigerator: General Electric, Maytag, Kenmore, Acme For Stove: General Electric, Frigidaire, Roper, Acme For Dishwasher: General Electric, KitchenAid, WhirlPool
Find the probability that they select General Electric for all three appliances.
Click here to see answer by solver91311(5072)  |
Question 130603This question is from textbook Statistics4
: I have tried to do this problem but I dont know how, could someone explain it to me? thanks
A landscape conractor bids on jobs where he can make $3000 profit. The probabilities of getting one, two, three, or four jobs per month are shown
Number of jobs 1 2 3 4
Probability .2 .3 .4 .1
Find the contractors expected profit per month.This question is from textbook Statistics4
Click here to see answer by stanbon(26259) |
Question 130590: A card is drawn from a standard 52-card deck. Calculate your expected value for the game. You pay $10 to play the game, which must be subtracted from your winnings. a heart is drawn, you win $20, otherwise you lose your $10.
What is the expected value?
Click here to see answer by stanbon(26259) |
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