Tutors Answer Your Questions about Probabilityandstatistics (FREE)
Question 872029: 1. A genetics expert has been studying genetic disorders for children of certain couples. In a study of 200 births, 25 of them contain the gene for this disorder.
a. Find a 95% confidence interval for the estimate of the population proportion.
b. What is the margin of error for this confidence interval?
c. Interpret this confidence interval verbally.
d. a "notso" famous genesist told you that he felt that the population proportion is 20%. What would you say to this person and why?
Click here to see answer by ewatrrr(22107) 
Question 872045: Good afternoon I need help with this problem I didn't get the right answer after my test results I need to know step by step, thank you so much for the help
A soft drink manufacturer claims that its 12 ounce cans do not contain, on average more than 30 calories a random sample of 16 cans of this soft drink, which were checked for calories contained a mean of 31.8 calorie with a standard deviation of 3 calories. Assume that the number of calories in the 12 ounce cans is normally distributed. Test the manufacturer's claim at the 5% significance level
Click here to see answer by ewatrrr(22107) 
Question 872059: Suppose that a pair of fair, standard 6sided dice are rolled fifteen times. What is the probability that a sum of 7 occurs exactly three times in the fifteen rolls? Please help. To solve this problem I must use either binomial distribution or expected value probability.
Click here to see answer by ewatrrr(22107) 
Question 871836: 50 students go bushwalking, 23 get sunburnt 22 get bitten by ants and 5 are both sunburnt and bitten. Determine the probability that a randomly selected student:
a)escaped being bitten.
b)was either bitten or sunburnt.
c)was bitten, given that he or she was sunburnt.
Note: Please provide workings.
Click here to see answer by richwmiller(15954) 
Question 872061: Suppose that 1,000 tickets are sold for a raffle. If there is one prize of $2,500, two prizes of $500, four prizes of $100, and thirteen prizes of $20, what is the expected value of a raffle ticket? Please help. I must use expected value formula but I'm stumped.
Click here to see answer by ewatrrr(22107) 
Question 872076: A paint manufacturing company claims that the mean drying time for its paint is not more than 45 minutes. A random sample of 20 gallons of pain selected from the production line of this company showed that the mean drying time for this sample is 50 minutes with a standard deviation of 3 minutes. Assume that the drying times for these paints have a normal distribution
Using the significance level would you conclude that the company's claim is true?
Thank you for taking the time and for your help!!!
Click here to see answer by ewatrrr(22107) 
Question 872074: A survey indicates 40% of households in the USA own CD players from a random sample of 250 households in the USA find the probability that the number of households who own CD players is:
a) exactly 95
b) between 105 and 110
c) at most 85
d) at least 95
Click here to see answer by ewatrrr(22107) 
Question 872056: Suppose that a jar contains 4 pens: 2 black, 1 blue, and 1 red. Three people select a pen at random from the jar, sign a document, and replace the pen in the jar before the next person selects a pen. What is the probability that none of the people use the red pen to sign the document?
Click here to see answer by Yzeph(21) 
Question 872056: Suppose that a jar contains 4 pens: 2 black, 1 blue, and 1 red. Three people select a pen at random from the jar, sign a document, and replace the pen in the jar before the next person selects a pen. What is the probability that none of the people use the red pen to sign the document?
Click here to see answer by Fombitz(25151) 
Question 872090: Suppose that a jar contains 4 pens: 2 black, 1 blue, and 1 red. Three people select a pen at random from the jar, sign a document, and replace the pen in the jar before the next person selects a pen. What is the probability that none of the people use the red pen to sign the document?
Click here to see answer by ewatrrr(22107) 
Question 872100: Five percent of workers in a city use public transportation to get to work. You randomly select 273 workers and ask them if they use public transportation to get to work. Complete parts (a) through (d).
a. Find the probability that exactly 19 workers will say yes.
Click here to see answer by ewatrrr(22107) 
Question 872099: Question text
Which of the following best describes tha area to the left of x = 28 where the mean of the distribution is 26.3 and the standard deviation is 1.04?
Select one:
a. approximately 5.1% of the area
b. approximately 98.4% of the area
c. approximately 89.4% of the area
d. approximately 94.8% of the area
Click here to see answer by ewatrrr(22107) 
Question 872105: 20. The sample size n, probability of success p, and probability of failure q are given for a binomial experiment. Decide whether you can use the normal distribution to approximate the random variable x.
n = 17 p = 0.32 q = 0.68
Click here to see answer by richard1234(6688) 
Question 872105: 20. The sample size n, probability of success p, and probability of failure q are given for a binomial experiment. Decide whether you can use the normal distribution to approximate the random variable x.
n = 17 p = 0.32 q = 0.68
Click here to see answer by ewatrrr(22107) 
Question 872104: The lifetimes of a certain brand of light bulbs are known to be normally distributed with a mean of 1,600 hours and a standard deviation of 400 hours. A random sample of 64 of these light bulbs is taken.
19) Referring to Table 74, what is the probability that the sample mean lifetime is more than 1,550 hours? 19) _____________
20) Referring to Table 74, the probability is 0.15 that the sample mean lifetime is more than how many hours?
Click here to see answer by ewatrrr(22107) 
Question 872097: Suppose that an automobile parts wholesaler claims that .5 percent of the car batteries in a shipment are defective. A random sample of 200 batteries is taken, and four are found to be defective.
(a) Use the Poisson approximation to find the probability that four or more car batteries in a random sample of 200 such batteries would be found to be defective, if we assume that the wholesaler's claim is true. (Round your answer to 4 decimal places.)
Click here to see answer by ewatrrr(22107) 
Question 872098: Determine the right z score that bounds and area under the standard normal curve of approximately 0.1239 if the z score for the left boundary is 1.08.
Select one:
a. Approximately, z = 0.33
b. Approximately, z = 2.14
c. Approximately, z = 1.16
d. Approximately, z = 0.60
Click here to see answer by ewatrrr(22107) 
Question 871914: )
The table below shows the numbers of two to fivebedroom houses in the Belmont neighborhood.
Number of Bedrooms Frequency
2 12
3 40
4 70
5 3
What is the probability that a randomly selected house will have 3 or fewer bedrooms?
A)
0.560
B)
0.416
C)
0.320
D)
0.584
Click here to see answer by jim_thompson5910(33401) 
Question 872160: three items were randomely selected from a bin that contains 3 defective and 7 nondefective lithium batteries. let the random variable X represent the number of defective batteries in the sample. A) what are the possible values of C? B)Obtain the PMF pf X. C) Calculate P(X=0) D) Calculate P(X is greater than or equal to 1)
Click here to see answer by stanbon(69061) 
Question 872140: So I have this problem and I don't understand it. Calculate the stard deviation to the nearest hundredth for each data set. The set is 41 49 43 39 40. Please help me I need to under stand this for my exam.
Click here to see answer by ewatrrr(22107) 
Question 872315: Please help??
In the least squares equation, Ŷ = 10 + 20X the value of 20 indicates ____________.
The Yintercept increases by 20 units for each unit increase in X
That Y increases by 20 units for each unit increase in X
That X increases by 20 units for each unit increase in Y
The error in prediction
Click here to see answer by reviewermath(988) 
Question 872333: According to a recent report, 0.28 is the probability that an American adult male has high cholesterol requiring treatment. Seven American adult males are randomly selected. Find the probability that exactly 2 of the 7 American adult males have high cholesterol requiring treatment. Would you please show the solution? Thank you!!!
Click here to see answer by jim_thompson5910(33401) 
Question 872339: In 2001, U.S. per capita consumption of bottled water was 18.8 gallons, and in 2006, U.S. per capita consumption of bottled water was 28.3 gallons. Let y be the number of gallons of bottled water consumed per capita in the U.S. in the year x, where x = 0 represents the year 2001.
(a) Which of the following linear equations could be used to predict the number of gallons of bottled water consumed per capita in the U.S. in a given year x, where x = 0 represents the year 2001?
A. y = 9.5x − 18,990.7
B. y = 9.5x + 18.8
C. y = 1.9x − 3783.1
D. y = 1.9x + 18.8
(b) Use the equation from part (a) to estimate the number of gallons of bottled water consumed per capita in the U.S. in 2014.
(c) Fill in the blanks to interpret the slope of the equation: The average rate of change of bottled water consumed per capita with respect to time is
______________________ per ______________. (Include units of measurement.)
Would you please show the solution? Thanks.
Click here to see answer by richwmiller(15954) 
Question 872336: A jar contains 18 red jelly beans, 22 yellow jelly beans, and 14 orange jelly beans. Suppose that each jelly bean has an equal chance of being picked from the jar. If a jelly bean is selected at random from the jar, what is the probability that it is not red?
Would you be kind to show the solution, please? Thank you.
Click here to see answer by manu17(3) 
Question 872380: 17. The population mean and standard deviation are given below. Find the required probability and determine whether the given sample mean would be considered unusual.
For a sample of n = 75, find the probability of a sample mean being greater than 213 if μ = 212 and
σ = 6.1.
Click here to see answer by stanbon(69061) 
Question 872380: 17. The population mean and standard deviation are given below. Find the required probability and determine whether the given sample mean would be considered unusual.
For a sample of n = 75, find the probability of a sample mean being greater than 213 if μ = 212 and
σ = 6.1.
Click here to see answer by ewatrrr(22107) 
Question 872379: 18. Use the central limit theorem to find the mean and standard error of the means of the indicated sampling distribution. Then sketch a graph of the sampling distribution.
The per capita consumption of red meat by people in a country in a recent year was normally distributed, with a mean of 115 pounds and a standard deviation of 37.2 pounds. Random samples of size 20 are drawn from this population and the mean of each sample is determined.
Click here to see answer by stanbon(69061) 
Question 872378: 9. The life span of a battery is normally distributed, with a mean of 2500 hours and a standard deviation of 50 hours. What percent of batteries have a life span that is more than 2575 hours? Would it be unusual for a battery to have a life span that is more than 2575 hours? Explain yours reasoning.
Click here to see answer by ewatrrr(22107) 
Question 872391: The average credit card debt of college seniors is $3962. If the debt is normally distributed with a standard deviation of $950, find these probabilities:
a) What is the probability that a randomly selected senior owes at least $1000?
b) The 10% of seniors that owe the most money owe more than what amount?
c) 95% of all seniors owe how much debt (centered about the mean)?
Click here to see answer by ewatrrr(22107) 
Question 872367: A worldwide organization of academics claims that the mean IQ score of its members is 115 , with a standard deviation of 15 . A randomly selected group of members of this organization is tested, and the results reveal that the mean IQ score in this sample is 115.8 . If the organization's claim is correct, what is the probability of having a sample mean of 115.8 or less for a random sample of this size?
Click here to see answer by ewatrrr(22107) 
Question 872375: 8. The mean incubation time for a type of fertilized egg kept at 100.6oF is 23 days. Suppose that the incubation times are approximately normally distributed with a standard deviation of 1 day.b. What is the probability that a randomly selected fertilized egg hatches between 21 to 23 days?
Click here to see answer by ewatrrr(22107) 
Question 872372: What proportion of the following sample of ten measurements lies within 1 standard deviation of the mean? Within 2 standard deviations? Within 2 standard deviations?
3 4 1 3 2
4 3 5 2 3
Proportion which lies within 1 standard deviation =?%
Proportion which lies within 2 standard deviation s=?%
Proportion which lies within 3 standard deviations=?%
Click here to see answer by ewatrrr(22107) 

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