# Why is the population shape a concern when estimating a mean?

22,584 results

1. ### statistics

Why is the population shape a concern when estimating a mean? What effect does sample size, n, have on the estimate of the mean? Is it possible to normalize the data when the population shape has a known skew? How would you demonstrate the central limit theorem to your ...
2. ### Research & Evaluation I

Why is the population shape a concern when estimating a mean? What effect does sample size, n, have on the estimate of the mean? Is it possible to normalize the data when the population shape has a known skew? How would you demonstrate the central limit theorem to your ...
3. ### college

why is the population shape a concern when estimating a mean
4. ### Statistics

You are getting ready to take a sample from a large population, and need to determine the appropriate sample size. You are estimating sales at a large chain of department stores. A previous survey from the same population found a standard deviation of \$18. What sample size is ...
5. ### Math (Statistic)

Considered the sampling distribution of a sample mean obtained by random sampling from an infinite population. This population has a distribution that is highly skewed toward the larger values. a) How is the mean of the sampling distribution related to the mean of the ...
6. ### Statistics

You are interested in estimating the mean of a population. you plan to take a random sample from the population and use the samples mean as an estimate of population mean. Assuming that the population from which you select your sample is normal, which of the statements about ...
7. ### stastics

Salaries of 31 college graduates who took a course in college have a mean, x of 66,700 a standard deviation , o of 17,120, construct a 90% confidence interval for estimating the population mean u.
8. ### Statistics

Find the margin of error for a 95% confidence interval for estimating the population mean when the sample standard deviation equals 100, with a sample size of (i) 400, (ii) 1600. What is the effect of the sample size? (b) Find the margin of error for estimating the population ...
9. ### Statistics

Find the margin of error for a 95% confidence interval for estimating the population mean when the sample standard deviation equals 100, with a sample size of (i) 400, (ii) 1600. What is the effect of the sample size? (b) Find the margin of error for estimating the population ...
10. ### Statistics

Salaries of 50 college graduates who took a statistics course in college have a​ mean, x of \$68,200. Assuming a standard​ deviation, σ​, of \$12,279​, construct a 95% confidence interval for estimating the population mean μ.
11. ### statistics

The scores of students on the ACT college entrance examination in a recent year had a normal distribution with a mean of 18.6 and a standard deviation of 5.9. A simple random sample of 50 students who took the exam is selected for study: A) What is the shape, mean, and ...
12. ### biology 12

what is the best method useful for estimating the populations of eagles, and why? i orginally thought counting the number of nests. but i don't know why its the best way of estimating the population. can you plesae correct me if im wrong and help me with the reasoning. thank ...
13. ### biology 12

what is the best method useful for estimating the populations of eagles, and why? i orginally thought counting the number of nests. but i don't know why its the best way of estimating the population. can you plesae correct me if im wrong and help me with the reasoning. thank ...
14. ### statistics

2. We would like to test whether the population mean is less than 40. Suppose that a hypothesis test is conducted to determine if the mean of the population has decreased or not. Describe what a Type II error would mean for this example. A) Reject H0 when the population mean ...
15. ### statistics

Assume the population distribution of FEV is normal with standard deviation 400 mLi. (a) find P(E) is n=15 and population mean is 2800 mLi (B) find P(E) is n=15 and the population mean is 2600mLi (C) How does P(E) depend on the population mean?
16. ### math statistics

The average price of a gallon of unleaded regular gasoline was reported to be \$2.34 in northern Kentucky (The Cincinnati Enquirer, January 21, 2006). Use this price as the population mean, and assume the population standard deviation is \$.20. 1. What is the probability that ...
17. ### math statistics

please help me I've waited for hours The average price of a gallon of unleaded regular gasoline was reported to be \$2.34 in northern Kentucky (The Cincinnati Enquirer, January 21, 2006). Use this price as the population mean, and assume the population standard deviation is \$....
18. ### stats

The mean tax-return preparation fee H&R Block charged retail customers last year was \$183 (The Wall Street Journal, March 7, 2012). Use this price as the population mean and assume the population standard deviation of preparation fees is \$50. Round your answers to four decimal...
19. ### Statistics

1. The scores of students on the ACT college entrance examination in a recent year had a normal distribution with a mean of 18.6 and a standard deviation of 5.9. A simple random sample of 60 students who took the exam is selected for study: a) What is the shape, mean(expected ...
20. ### Statistics

The following is a histogram (right skewed) of the first ten terms of a geometric distribution with p = .4. The mean of this distribution is 2.5 and the standard deviation is approximately 1.93. What's the shape of the distribution of sample means for simple random samples of ...

For a continuous random variable x, the population mean and the population standard deviation are 80 and 15 respectively. You extract a sample of 25 elements from this population. The mean of the sampling distribution of the sample mean is
22. ### social statistics

a smoking researcher is interested in estimating the average age when cigarette smokers first began to smoke. Taking a random sample of 25, she determines a sample mean of 16.8 years and a sample deviation of 1.5 years. Construct a 95% confidence interval to estimate the ...
23. ### Statistics

An admissions director wants to estimate the mean age of all students enrolled at a college. The estimate must be within one year of the population mean. Assume the population of ages is normally distributed. Determine the minimum required sample size to construct a 80% ...
24. ### elizabeth high school

. An admissions director wants to estimate the mean age of all students enrolled at a college. The estimate must be within one year of the population mean. Assume the population of ages is normally distributed. Determine the minimum required sample size to construct a 90% ...
25. ### statistics

An important indicator of lung function is forced expiratory volume(FEV), which is the volume of air that a person can expire in one second. Dr. Jones plans to measure FEv in a random sample of n young women from a certain population, and to use the sample mean as an estimate ...
26. ### statistics

The average price of a gallon of unleaded regular gasoline was reported to be \$2.34 in Northern Kentucky use this price as a population mean population standard deviation is \$.20. question. what is the probability that the mean price for a sample of 30 station is good then \$....
27. ### statistics

If you want to be 95% confident of estimating the population proportion to within a sampling error of and there is historical evidence that the population proportion is approximately 0.40, what sample size is needed?
28. ### statistics

In the distributions of two populations combined mean of fourteen observations is 14 and if the sum of the first seven observations for population one and mean of population two are 90 and 16 respectively ,then find the last (eighth)observation of population one and the mean ...
29. ### Ecology

What are the types of population density measure and how each may be determined? Airkon Population density is a measurement of the number of people in an area. It is an average number. Population density is calculated by dividing the number of people by area. Population ...
30. ### stats

A sample of 12 observations is selected from a normal population for which the population standard deviation is known to be 4. The sample mean is 19. (Round your answers to 3 decimal places.) (a) The standard error of the mean is The 90 percent confidence interval for the ...
31. ### statistics

14) A population of N = 20 scores has a mean of µ = 15. One score in the population is changed from X = 8 to X =28. What is the value for the new population mean?
32. ### statistics

Use the given information to find the minimum sample size required to estimate an unknown population mean u. How many adults must be randomly selected to estimate the mean FICO (credit rating)score of working adults in a country? We want 95% confidence that the sample mean is ...
33. ### statistics

A statistics practitioner formulated the following hypothesis: Ho: population mean=200 H1: population mean<200 sample mean=190 n=9 population standard deviation=50 Calculate the p-value of the test
34. ### statistics

A random sample of n = 4 scores is selected from a population with ƒÝ = 80 and ƒã = 20. On average, how much difference would you expect between the sample mean and the population mean? a. 0 points (the sample mean should be the same as the population mean) b. 5 points c. ...
35. ### english

selection of hiking shoes should be your first concern.even a one day hike can be misery without comfortable shoes. the most effective combination of sentences 3and4 would include which of the following groups of words? a)concern,also even b)concern,although even c)concern,...
36. ### stats

Consider an infinite population with 25% of the elements having the value 1, 25% the value 2, 25% the value 3, and 25% the value 4. If X is the value of a randomly selected item, then X is a discrete random variable whose possible values are 1, 2, 3, and 4. (a) Find the ...
37. ### statistics

How do we compute sample size fluctuations? Suppose we have a population of 16000 and a sample size of 30, and the number of samples 1000, what will be the impact on population mean and standard deviation when the population is normally distributed? When the population is ...
38. ### Geometry

A)What was the mean population of the six continents or land masses that were habitable in 2000? B) What was the mean population in 1950? C) What was the percent incease in the mean population from 1950 to 2000?
39. ### Statistics

he Oil Price Information Center reports the mean price per gallon of regular gasoline is \$ 3.79 with a population standard deviation of \$ 0.18. Assume a random sample of 40 gasoline stations is selected and their mean cost for regular gasoline is computed. 1. What is the ...
40. ### statistics

Suppose a population distribution of SAT scores has population mean 500 and population standard deviation 100. What is the mean of the sampling distribution of sample means, ybar , calculated from samples of size n = 36
41. ### Statistics/Probability

The standard deviation of the masses of articles in a large population is 4.55 kg. Random samples of size 100 are drawn from the population. Find the probability that a sample mean will differ from the population mean by less than 0.8 kg.
42. ### statistics

An IQ test was administered to a random sample of 26 mental patients and the mean was found to be 99.7. For this test, the population values are known to be normally distributed and with a population standard deviation of 15. Construct a 90% confidence interval for the mean IQ...

FORMAT INSTRUCTIONS Each question requires the use of MINITAB to solve. Please submit your work as a WORD or similar document. You can prepare this by cutting and pasting the results generated in MINITAB to such a document. Then you can edit that file with any required ...

FORMAT INSTRUCTIONS Each question requires the use of MINITAB to solve. Please submit your work as a WORD or similar document. You can prepare this by cutting and pasting the results generated in MINITAB to such a document. Then you can edit that file with any required ...
45. ### statistics

Use the given information to find the minimum sample size required to estimate an unknown population mean μ. How many commuters must be randomly selected to estimate the mean driving time of Chicago commuters? We want 99% confidence that the sample mean is within 4 ...
46. ### Math

Q1. A population has a mean of µ = 80 with σ = 20. a. If a single score is randomly selected from this population, how much distance, on average, should you find between the score and the population mean? 20 because the standard deviation is 20 b. If a sample of n = 4 ...
47. ### statistics

A simple random sample of 60 items resulted in a sample mean of 80. The population standard deviation is 15. a) Compute the 95 % confidence interval for the population mean. b) Assume that the same sample mean was obtained from a sample of 120 items. Provide a 95% confidence ...
48. ### Math- Statistics

A random sample of size 36 is to be selected from a population that has a mean μ = 50 and a standard deviation σ of 10. * a. This sample of 36 has a mean value of , which belongs to a sampling distribution. Find the shape of this sampling distribution. * b. Find the ...
49. ### Statistics

1. In thinking about doing statistical analysis, the sample mean should be interpreted as: A.)a constant value that is equal to the population mean. B.) a constant value that is approximately equal to the population mean. C.) a random variable that is approximately equal to ...
50. ### statistics

please help me I've waited for hours The average price of a gallon of unleaded regular gasoline was reported to be \$2.34 in northern Kentucky (The Cincinnati Enquirer, January 21, 2006). Use this price as the population mean, and assume the population standard deviation is \$....
51. ### statistics help

The branch manager of an outlet (Store 1) of a nationwide chain of pet supply stores wants to study characteristics of her customers. In particular, she decides to focus on two variables: the amount of money spent by customers and whether the customers own only one dog, only ...
52. ### Statistics

The mean television viewing time for Americans is 15 hours per week. Suppose a sample of 60 Americans is taken to further investigate viewing habits. Assume the population standard deviation for weekly viewing ime is o = 4 hours. A What is the probability the sample mean will ...
53. ### Stats

a population of 8 scores has a mean of 11. If one of the scores in this population is changed from x=9 to x=25, what value would be obtained for the new population mean?
54. ### Stats

A sample of 400 items is taken from a population whose standard deviation is 10. The mean of the sample is 40. Test whether the sample has come from a population with mean 38. Also calculate 95% confidence interval for the population.
55. ### Statistics

If the mean family size is 4.75 what is the total population of a city of 25000 families? Is it correct if I calculate it as follows: Mean: (x : 25000) = 4.75 Mean: x = 118750 number of population
56. ### statistics

A population has a mean of 300 and a standard deviation of 50. Suppose a sample of size 125 is selected and is used to estimate . What is the probability that the sample mean will be within +/- 3 of the population mean (to 4 decimals)?
57. ### Statistics

A population has a mean of 200 and standard deviation of 50 and simple random sample size of 100 and x is used to estimate u. What is the probility that the sample mean will be within plus or minue 5 of the population mean?
58. ### sample size/ standard deviations

How do we compute sample size fluctuations? Suppose we have a population of 16000 and a sample size of 30, and the number of samples 1000, what will be the impact on population mean and standard deviation when the population is normally distributed? When the population is ...
59. ### Statistics

The number of books sold over the course of the three-day book fair were: 365, 303, 401. Assume that samples of size 2 are randomly selected with replacement from this population of three values. a. List the different possible samples, and find the mean of each of them. b. ...
60. ### statistics

5) The lifetime of a medical device s a normally distributed rv with standard deviation of 2 years. An experiment is conducted to test 15 medical devices and find their lifetimes to be: a. If the population mean is known to be 15 years, what is the probability that the mean ...
61. ### statistics

In performing a hypothesis test, the null hypothesis is population mean = 6.9 and the alternative hypothesis is population mean ≠ 6.9, a random sample of 16 items is selected. The sample mean is 7.1 and the sample standard deviation is 2.0. The population is approximated...
62. ### sda high

A population has a mean of 200 and a standard deviation of 50. Suppose a simple random sample of size 100 is selected and is used to estimate μ. What is the probability that the sample mean will be within 5 of the population mean?
63. ### statistics

Scores on a national writing exam are approximately normally distributed, with a mean of 490 and a standard deviation of 20. Consider random samples of size 25 from the population of test takers. describe the sampling distribution of a sample mean. shape mean= standard ...
64. ### Statistics (42)

A simple random sample of 60 items resulted in a sample mean of 96. The population standard deviation is 16. a. Compute the 95% confidence interval for the population mean (to 1 decimal). ( , ) b. Assume that the same sample mean was obtained from a sample of 120 items. ...
65. ### Statistics

The estimated standard error, sM, provides a measure of the average or standard distance between _____. a score and the population mean (X and ì) a sample mean and the population mean (M and ì) a score and the sample mean (X and M) None of the other options is correct.
66. ### Satistics

**I don't want the answer, I want to know how to set the problem up and the formula that I need to use. I am online with a tutor right now, and they can't help me. :-( The average price of a gallon of unleaded regular gasoline was reported to be \$2.34 in northern Kentucky (The...
67. ### Statistics

A researcher found a sample proportion of 0.94 for estimating the population proportion of freshmen at a university who had Facebook accounts. If the standard deviation of the sampling distribution of the sampling proportion is 0.02, what is a 95% confidence interval for the ...
68. ### calculus

A MANUFACTURE OF LIGHTBULBS HASS SAMPLED 40 BULBS IN ORDER TO DETERMINE THE POPULATION MEAN LIFE OF THE BULBS. tHE SAMPLE MEAN WAS 1200 HOURS WITH A STANDARD DEVIATION OF 100. tHE MANUFACTURER WOULD LIKE TO KNOW, WITH 95% CONFIDENCE, THE INTERVAL VALUES FOR THE POPULATION MEAN.
69. ### statistics

A population is normally distributed with mean 30, population SD =10, Sample size 25. What are the mean and variance of the distribution of means, respectively?
70. ### statistics

A population of N = 10 scores has a mean of μ = 24. If one person with a score of X = 42 is removed from the population, what will be the value for the new mean?
71. ### statistics

Sample with size n = 100 has mean = 30. Assuming the population standard deviation is 8, construct 95% confidence interval for population mean.
72. ### statistics

Sample with size n = 100 has mean = 30. Assuming the population standard deviation is 8, construct 95% confidence interval for population mean.
73. ### Statistics

A local grocery store wants to estimate the mean daily number of gallons of milk sold to customers. Assume the number of gallons sold follows the normal distribution, with a population standard deviation of 5.10 gallons. A random sample of 60 days shows that the mean daily ...
74. ### statistics

If random samples, each with n = 36 scores, are selected from a normal population with m = 80 and s = 18, how much difference, on average, should there be between a sample mean and the population mean?
75. ### statistics

a distribution of scores has 6, but the value of the mean is unknown, a researcher plans to select a sample from the population in order to learn more about the unknown mean, if the sample consist of n= 9 scores , how accurately should sample mean represent the population mean
76. ### Statistics

Dr. Hernandez plans to measure FEV in a random sample of n young women from a certain popu- lation, and to use the sample mean y ̄ as an estimate of the population mean. Let A be the event that Hernandez’s sample mean will be within ±100 ml of the popula- tion mean. ...
77. ### Economics

select a country and an economic concern, such as population, unemployment, etc. Search the Library and Internet for data sets for the concern that you have chosen. Where were you able to find data sets? What is the relationship between the variable that you selected and the ...
78. ### statistic

1. A distribution has a standard deviation of   12. Find the z-score for each of the following locations in the distribution. a. Above the mean by 3 points. b. Above the mean by 12 points. c. Below the mean by 24 points. d. Below the mean by 18 points. For the following ...
79. ### Statistics

Which of the following statements correctly interprets a 95% confidence interval on a population mean? a. It is a single point estimate b. Used to quantify the certainty of the sample standard deviation c. A 99% confidence interval is narrower than the 95% confidence interval ...
80. ### Statistics

For a population with a mean of (mew) = 50 and a standard deviation of 10, how much error, on average, would you expect between the sample mean (M) and the poulation mean for: a) a sample of n=4 scores b) a sample of n=16 scores c) a sample of n=25 scores Are the sample mean (...
81. ### math

Describe the distribution of sample means (shape, expected value, and standard error) for samples of n  36 selected from a population with a mean of μ  100 and a standard deviation of   12.
82. ### Statistics (urgent)

A beverage comopany uses a machine to automatically fill 1-liter bottles. Assume that the population of volumes is normally distributed. The company wants to estimate the mean volume of water to within 1 ML. Determine the minimum sample size required to construct a 95% ...
83. ### Statistics

Calculate the following: a) Determine the sample size necessary to estimate a population mean to within 1 with a 90% confidence given that the population standard deviation is 10. b) Suppose that the sample was calculated at 150. Estimate the population mean with 90% confidence.
84. ### statistics

Given the oft-cited statistic that 66.7% of the American public is overweight or obese, you are interested in comparing college students BMI level to the general population. Assuming that the general population has a BMI of (μ) = 27.5 using α level of .05, you ...
85. ### Statistics (39)

Suppose a random sample of size 40 is selected from a population with = 9. Find the value of the standard error of the mean in each of the following cases (use the finite population correction factor if appropriate). a. The population size is infinite (to 2 decimals). b. The ...
86. ### Economics (39)

Suppose a random sample of size 40 is selected from a population with = 9. Find the value of the standard error of the mean in each of the following cases (use the finite population correction factor if appropriate). a. The population size is infinite (to 2 decimals). b. The ...
87. ### statistics

A biologist reports a confidence interval of (3, 2, 3, 8) when estimating the mean height in (in centimeters) of a sample of seedlings. The estimated margin of error is __________ , The sample mean is ________.

The U.S. Dairy Industry wants to estimate the mean yearly milk consumption. A sample of 16 people reveals the mean yearly consumption to be 60 gallons with a standard deviation of 20 gallons. a. What is the value of the population mean? What is the best estimate of this value...
89. ### Statistics

A normally distributed population has a mean of 40 and a standard deviation of 12. What does the central limit theorem say about the sampling distribution of the mean if samples of size 100 are drawn from this population.

i need help! how you Estimating quotients how you solve a problem. like this one? 195 divided 4 in estimating quotient?
91. ### statistics

Suppose a random sample of size 50 is selected from a population with σ = 10. Find the value of the standard error of the mean in each of the following cases (use the finite population correction factor if appropriate). a. The population size is infinite (to 2 decimals). ...
92. ### statistics

Suppose a random sample of size 50 is selected from a population with σ = 10. Find the value of the standard error of the mean in each of the following cases (use the finite population correction factor if appropriate). a. The population size is infinite (to 2 decimals). ...
93. ### math

1. Consider the following scenario: A random sample obtained from a population has a mean of µ=100 and a standard deviation of σ = 20. The error between the sample mean and the population mean for a sample of n = 16 is 5 points and the error between a sample men and ...
94. ### statistics

A basketball scout randomly selected 144 players and timed how long each player took to perform a certain drill. The times in this sample were distributed with a mean of 8 minutes. The population standard deviation was known to be 3 minutes. A. find the critical value for a 95...
95. ### statistics

a population has mean 15 and standard deviation 5. if 68% of the values in the population are between 10 and 20, the population cannot be normal
96. ### Statistics

A population has µ=100 and õ=20. If you select a single score from this population, on the average, how close would it be to the population mean? Explain your answer
97. ### Statistics

Suppose a researcher wants to study the effectiveness of a new reading program for students who have not acquired the necessary reading skills by the time they reach the 8th grade. A randomly selected group of 50 students from a local junior high with poor reading skills will ...
98. ### Statistics

Problem 1 Use the Old Faithful data labelled Duration as a sample for problem 1. a. Determine the proportion of instances that the duration was less than 240 seconds. Also express the proportion as a percent. (hint: proportion is number of successes divided by total number. b...
99. ### Statistic

For a population with a mean of μ  70 and a standard deviation of   20, how much error, on average, would you expect between the sample mean (M) and the population mean for each of the following sample sizes? a. n  4 scores b. n  16 scores c. n  25 scores
100. ### Statistics

A population has u=100 σ=20. If you select a single score from this population, on the average, how close would it be to the population mean? Explain your answer