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August 23, 2014

Search: Statistics Question (Confidence Interval)

Number of results: 31,738

statistics
Refer to Table 1 in the article Snail Shells in a Practical Application of Statistical Procedures in the Electronic Reserve Readings. Find the margin of error, E, with a confidence interval of your choosing (50-99%). What is the significance of choosing a confidence interval...
April 26, 2012 by len

Statistics
Which of the following statements best describes the uncertainty associated with a 95% confidence interval for a population proportion, computed from a simple random sample? A. We don't know whether the particular confidence interval is successful or not, but 95% of ...
May 18, 2012 by Mary

Statistics
The standard deviation for a population is σ = 15.3. A sample of 36 observations selected from this population gave a mean equal to 74.8. a) Make a 90% confidence interval for μ b) Construct a 95% confidence interval for μ. c) Determine a 99% confidence interval...
November 21, 2013 by ----

Statistics
The 95% confidence interval is: (a) Larger than the 99% confidence interval (b) Smaller than the 99% confidence interval (c) The same as the 99% confidence interval
October 28, 2007 by Thano

Statistics
In 1998 a San Diego Reproductive clinic reported 49 live births to 207 women under the age of 40 who had previously been unable to get pregnant. Using the 90% confidence interval calculated above, would it be misleading for the clinic to report a success rate of 25%? A) Yes, ...
October 27, 2013 by Jeffrey

Statistics
Answer the question Yes or No. Sam computed a 90% confidence interval for from a specific random sample of size n. He claims that at the 90% confident level, his confidence interval does not contain . Is this claim correct? Answer a. No b. Yes
July 7, 2012 by Desperate

Statistics
1. A certain population follows a normal distribution, with mean m and standard deviation s = 2.5. You collect data and test the hypotheses H0: m = 1, Ha: m 1. You obtain a P-value of 0.022. Which of the following is true? Why? a. A 95% confidence interval for m will include ...
November 29, 2008 by Latoya

Statistics
A confidence interval for a population mean has a margin of error of 3.1. a)Determine the length of the confidence interval. b)If the sample mean is 56.7, obtain the confidence interval.
May 21, 2014 by Anonymous

Statistics
We have calculated a 95% confidence interval for a proportion and would prefer the confidence interval to be more precise, that is narrower. Using the same sample, we can narrow the confidence interval using which of the following? A) increasing the confidence level B) ...
October 27, 2013 by Nick

Statistics
Multiple Choice Which of the following statements is true about the 95% confidence interval of the average of a sample? A) 95 of 100 avgs of samples will be within the limits of the confidence interval. B) There is a 95% chance the avg of the population to be within the limits...
July 26, 2013 by Andrew

Statistics
A random sample of 90 observations produced a mean that = 25.9 and a standard deviation s =2.4 (a)Find a 95% confidence interval for u (b)Find a 90% confidence interval for u (c)Find a 99% confidence interval for u (Use integers or decimals for any number in the expression. ...
March 23, 2014 by Carol Harper

statistics
What do confidence intervals represent? What is the most controllable method of increasing the precision of or narrowing the confidence interval? What percentage of times will the mean, or population proportion, not be found within the confidence interval?
April 30, 2010 by Amy

Statistics
A confidence interval was used to estimate the proportion of statistics students that are females. A random sample of 72 statistics students generated the following 90% confidence Interval: (.43, .63). based on the interval above, is the population proportion of females equal ...
November 22, 2010 by Anonymous

Statistics
. As the sample size increases The confidence interval also increases (gets larger) The confidence interval decreases (gets smaller) The confidence interval stays the same The population mean increases.
June 22, 2010 by Jacob

Statistics
You are given the following information obtained from a random sample of 6 observations. Assume the population has a normal distribution. 13 14 17 14 17 15 a. What is the point estimate of ? b. Construct an 80% confidence interval for . c. Construct a 98% confidence interval...
November 12, 2013 by Katie

Elementary Statistics
1) Construct a confidence interval of the population proportion at the given level of confidence. x=60,n=300, 99% confidence. The 99% confidence interval is (_,_) 2) A researcher wishes to estimate the proportion of adults who have high-speed internet access. What size sample ...
June 6, 2012 by Erin

Math Statistics
5. Students in an introductory statistics class were asked to report the age of their mothers when they were born. Summary statistics include Sample size: 36 students Sample mean: 29.643 years Sample standard deviation: 4.564 years a. Calculate the standard error of this ...
July 29, 2013 by James

Statistics:Significance Test and Confidence Interv
Significance Test and Confidence Intervals In General: The article contains a 95% confidence interval. Would the margin of error in a 99% confidence interval computed from the same data be less, the same, or greater?
September 11, 2007 by Carma

Statistics
Please help!! I have no idea how to do this question. 14. A sample of 40 CDs from your collection showed a mean length of 52.74 minutes with a standard deviation of 13.21 minutes a. Construct the 95 percent confidence interval for the mean. b. Construct the 95 percent ...
October 31, 2011 by Kristi

statistics
Consider a 90% confidence interval for μ. Assume σ is not known. For which sample size n=10 or n=20, is the confidence interval longer?
October 31, 2011 by Morgan

Statistics
Suppose x has a mound-shaped distribution with sigma = 9 . A random sample of size 36 has sample mean 20. Is it appropriate to use a normal distribution to compute a confidence interval for the population mean m? Explain. Find a 95% confidence interval for m. Explain the ...
April 27, 2013 by Steph

statistics
Consider a 95% confidence interval for a population mean constructed from a random sample of 250 observations taken from a Normal population. Sigma is known to be 14. If we were to construct another 95% confidence interval, this time using 1,000 observations, how would the ...
February 20, 2011 by AMY

statistics
Consider a 95% confidence interval for a population mean constructed from a random sample of 250 observations taken from a Normal population. Sigma is known to be 14. If we were to construct another 95% confidence interval, this time using 1,000 observations, how would the ...
February 20, 2011 by AMY

statistics
P(proportion) is 0.05446, n is 863 and a 90% confidence interval is required. What is this confidence interval?
December 23, 2011 by blue

statistics
The Frayed Nerves Anxiety Scale (FNAS) is used to measure the anxiety level of people on a scale from 0 to 1000. Four students were randomly chosen and given the FNAS before their second exam. Their scores were 700, 653, 740, and 707. The standard deviation sigma of the test ...
October 17, 2011 by Anand

Statistics
Use the sample data and confidence level to construct the confidence interval estimate of the population p....n=5200, x=4821, 99% confidence
May 1, 2013 by Tangee

Environmental Management
A. The 95% confidence interval is: (a) Larger than the 99% confidence interval (b) Smaller than the 99% confidence interval (c) The same as the 99% confidence interval
July 13, 2009 by Jox

statistics
10. Using the results of a Newsweek poll conducted in March of 2009, a 90% confidence interval on the proportion of adult Americans who have a favorable opinion of Barack Obama is given by (0.699, 0.741). If everything else is the same, but the confidence level increases, ...
May 8, 2013 by ali awan

Statistics
The confidence interval below for the population variance is based on the following sample statistics: n = 25, x-bar = 31.1, and s = 4.2. 9.29 < standard deviation squared < 42.82 What is the degree of confidence?
July 22, 2012 by Ann

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 ...
September 15, 2010 by Beata Chmielewska

statistics
The following list is a sampling of the costs of various statistics textbooks used at several colleges. Give the upper confidence limit for a 95% confidence interval estimate for the mean cost of all statistics textbooks. 109.95; 92.00; 96.70; 84.85; 92.60; 84.45; 90.95; 77.00...
July 31, 2014 by martha

statistics
Help!!!!!! A confidence interval estimate for the population mean is given to be (39,90, 48.11) If the standard deviation is 11.473 and the sample size is 52 determine the maximum error of the estimate. determine the confidence level used for the given confidence interval
November 9, 2011 by amy

Math-Stat Help
In a random sample of 78 teenagers, 32 admit to texting while driving. Construct a 98% confidence interval for the percentage of teenager that text while driving. Start by showing that conditions for constructing a confidence interval are met. 1) Check conditions 2) confidence...
April 11, 2013 by MELISSA

Math-Statistics
Find a confidence interval for assuming that each sample is from a normal population. a. P x = 14, = 4, n = 5, 90 percent confidence b. P x = 37, = 5, n = 15, 99 percent confidence c. P x = 121, = 15, n = 25, 95 percent confidence Need to show my work/formula ...
December 6, 2011 by Richard

Statistics:Z and T Statistics: Confidence Interva
Z and T Statistics: Confidence Intervals and Significance Tests: A friend who hears that you are taking a statistics course asks for help with a specific chemistry lab report. She has made four independent measurements of the specific gravity of a compound. The results are : 4...
September 11, 2007 by Carma

BIOLOGY - LAB
What is Confidence Interval? Is it better to have a large Confidence Interval or a small Confidence Interval? Briefly explain.
March 24, 2009 by biology

statistics
A sample of n = 9 has a mean of M = 72 with SS = 162. Use the sample to make a point estimate of and to construct the 90% confidence interval for . (Round all answers to two decimal places = ? ? ( ? ) The 90% confidence interval for : ( ? , ? )
November 4, 2011 by Anonymous

statistics
A sample of n = 9 has a mean of M = 72 with SS = 162. Use the sample to make a point estimate of and to construct the 90% confidence interval for U. (Round all answers to two decimal places.) U = ? ? ( ?) The 90% confidence interval for U: ( ? , ? )
November 4, 2011 by Anonymous

Statistics
A confidence interval was used to estimate the proportion of statistics students that are females. A random sample of 72 statistics students generated the following 90% confidence interval: (0.438, 0.642). Based on the interval above, is the population proportion of females ...
August 11, 2008 by Student

Statistics
Use the sample data and confidence level to construct the confidence interval estimate of the population proportion p. n=500, x=350, 90% confidence ?<p<? (Round to three decimal places as needed.)
April 30, 2013 by Rob

Statistics
Express the confidence interval using the indicated format. Express the confidence interval -0.129 < p < 0.631 in the form of p E.
July 21, 2014 by tray

Statistics Question (Confidence Interval)
A sample of 15 recent college graduates found that starting salaries for attorneys in New York City had a mean of $102,342 and a standard deviation of $21,756. Construct a 95% confidence interval for the average starting salary of all attorneys in the city. A. (89869.82, ...
March 14, 2012 by Mark

Statistics
Should companies use the same confidence interval each time a confidence interval is determined or should the level change based on situations? If it changes based on situations, what type of situations might call for higher confidence levels?
April 6, 2012 by John

statistics
How large a sample would be needed to form a 90% confidence interval for the mean nicotine content of a brand of cigarettes if the nicotine content has a normal distribution with sigma equal to 8.5 mg and the width of the interval (the length of the confidence interval) equal ...
November 17, 2013 by Alex

Statistics
When consumers apply for credit, their credit is rated using the FICO score. A bank manager used a random sample of the credit scores of 18 customers and determined the following 95% confidence interval: (613.6, 708.0) If the sample used 45 customers rather than 18 customers, ...
November 6, 2013 by Katelyn

Statistics 101
A researcher plans to use a random sample of n= 500 families to estimate teh mean monthly family incomefor a large population. a 99% confidence interval based on the sample would be _________ than 90% confidence interval.
February 25, 2014 by Deedy

Math Statistics
Students enrolled in an introductory statistics course at a university were asked to take a survey that indicated whether the student has a visual or verbal learning style. Of the 39 students who took the survey, 25 were judged to have a visual learning style and 14 were ...
July 25, 2013 by James

Statistics
What is meant by the 95% confidence interval of the mean ? That 95% of my sample is OK to do more tests. That I am 95% confident that the confidence interval will contain the parameter being estimated. That 5% of my sample is not OK. That I am 95% sure that the population mean...
June 22, 2010 by Jacob

statistics
What is meant by the 95% confidence interval of the mean ? That 95% of my sample is OK to do more tests. That I am 95% confident that the confidence interval will contain the parameter being estimated. That 5% of my sample is not OK. That I am 95% sure that the population mean...
August 17, 2010 by Karen

statistics
A 90% confidence interval for a population mean based on 144 observations is computed to be (2.7,3.4). How many observations must be made so that 90% confidence interval will specify the mean to within 0.2
October 6, 2011 by Prakash

statistics
Pleas HeLp!!!!!!!!!! A random sample of the test scores of 100 applicants for college entry at a large junior college showed a mean score of 72.6. Determine a 99%, 95%, and 90% confidence interval for the m mean score of all applicants at the junior college. Assume the ...
September 17, 2011 by courntey

Statistics
When estimating a population mean μ, where the population standard deviation σ is known, we can: a. choose a larger z value, construct a wider confidence interval, and achieve a lower confidence level b. choose a smaller z value, construct a narrower confidence ...
November 14, 2012 by Melanie

Statistics
Hoping to lure more shoppers downtown, a city builds a new parking garage in the central business district. The city hopes that the parking revenues will pay for the garage. During a recent two month period (44 days), the city statistician calculated the 95% confidence ...
November 10, 2013 by Katie

statistics
Using the 95% level of confidence, what is the confidence interval for the proportion of households represented at a town meeting
April 21, 2014 by Jay

Statistics
A scientist in Smallville tested the cholesterol of a random sample of 35 town residents. He constructed the following confidence interval: t-interval for μ: with 99.00% Confidence: 188 < μ(Cholesterol) < 206 What is the margin of error? A) 18 B) 9 C) 1.09 D) ...
November 6, 2013 by Katelyn

Math
What effect will an outlier have on a confidence interval that is based on a small sample size? A) The interval will be smaller than an interval without the outlier. B) The interval will be the same with or without the outlier. C) The confidence interval will be wider than an ...
November 28, 2009 by Jennifer

Statistics
A city ballot includes a local initiative that would legalize gambling. The issue is hotly contested, and two groups decide to conduct polls to predict the outcome. The local newspaper finds that 53% of 1200 randomly selected voters plan to vote "yes," while a college ...
October 27, 2013 by Jeffrey

statistics
Find the critical value zc necessary to form a confidence interval at the given level of confidence. a. 90% = 1.645 b. 85% = 1.8025
April 1, 2010 by looking for someone to varify my work please

Statistics
How would I find the confidence level (in %) if I am given the standard deviation, size of the random sample, and confidence interval?
April 3, 2013 by C

statistics
a companys ceo wanted to estimate the percentage of defective product per shipment. in a sample contianing 600 products he found 45 defective product. a. find 99% confidence interval for the true porporton of defective product show calcultions and explain process used to ...
August 23, 2011 by crystal

statistics
A data set includes body temperatures of healthy adult humans for which x= 98.2 and s=0.64 F. Complete parts a) and b) below a) what is the best point estimate of the mean body temperature of all healthy humans? The best point estimate is F. b) Using the sample statistics, ...
November 19, 2013 by anonymous

statistics
A school psychologist is trying to determine the lower boundary of a confidence interval for a IQ measure that has a mean of 100 and a standard deviation of 30 and a sample size of 100. What is the lower boundary if she was to create a 95% confidence interval?
July 1, 2011 by Haywood

Statistics
A 95% confidence interval for a population mean, ?, is given as (18.985, 21.015). This confidence interval is based on a simple random sample of 36 observations. Calculate the sample mean, x ?, and the sample standard deviation, s. Assume that all assumptions and conditions ...
June 18, 2012 by Mike

Statistics
If someone gives you a sample mean and a standard deviation, you can find a confidence interval. But what if someone gives you the confidence interval instead and asks you to find the sample mean? How can you do that? Here's an example: a 95% confidence interval for a mean is ...
October 4, 2011 by Hope

statistics
When a (1 - )100% confidence interval is formed for , what is the probability that the interval will not contain within its limits?
November 18, 2008 by Kennon

Statistics
If a 90%, 95% and 99% confidence interval are found for a population mean, how are the three interval estimates related to each other?
December 7, 2008 by Cecilia

statistics
Lorraine was in a hurry when she computed a confidence interval for μ. Because σ was not known, she used a Student's t distribution. However, she accidentally used degrees of freedom n instead of n - 1. Will her confidence interval be longer or shorter than one found...
February 18, 2012 by jr

Statistics
(25 pts, 5 pts each) The ounces of coffee that a machine dispenses in 5-ounce cups have normally distributed. Suppose a sample of size 6 was taken from this machine, as shown as follows: 5.05 5.03 5.10 5.02 4.98 5.00 (for all calculations, keep at least six decimal places) (1...
May 9, 2014 by Trell

Lab Math/Statistics
The 95% confidence interval for a quality control specimen is 9.2-10.2 mg/dl. My question is, how do I figure out the coefficient of variation (%CV) with only this information?
April 13, 2012 by Jason

statistics
A confidence interval or significance test is called stable if the confidence level or P-value does not change very much when the conditions for use of the procedure are violated
April 6, 2011 by A confidence interval or significance test is call

statistics
In a sample of 100 steel wires the average breaking strength is 50 kN, with a standard deviation of 2 kN. a. Find a 95% confidence interval for the mean breaking strength of this type of wire. b. An engineer claims that the mean breaking strength is between 49.7 kN and 50.3 ...
October 29, 2011 by Don't get it!! :(

Statistics
A random sample of 14 college female students revealed their average height was 66.1 inches. a) How many students should be in a samle if a 95% confidence interval is to have a margin of error of only plus/minus 1 inch? Is that the only information you were given? Were you not...
July 30, 2007 by Kasey

Statistics
In a study to estimate a population mean, i start with a sample size 10 and calculate the 95% confidence interval. Suppose i am not satisfied with the size of the confidence interval and want to reduce it by half. Give an estimate of sample size that i need.
August 23, 2010 by Zodra

statistics
The new Twinkle bulb is being developed to last more than 1000 hours. A random sample of 100 of these new bulbs is selected from the production line. It was found that 48 lasted more than 1000 hours. Find the point estimate for the population proportion, the margin of error ...
April 6, 2010 by looking for someone to varify my work please

math
With a confidence level of .95 and a confident interval of 5 and a population of 20,000 what is the sample size? With a confidence level of .99 and a confident interval of 5 and a population of 20,000 what is the sample size? Finally, using the sample size for question 1 and 2...
October 15, 2007 by sam

Statistics
Which is true about a 99% confidence interval for a population proportion based on a given sample? I. We are 99% confident that the population proportion is in our interval. II. There is a 99% chance that our interval contains the sample proportion. III. The interval is wider ...
October 28, 2013 by Fred

Statistics
The population standard deviation is estimated to be $300. If a 98% confidence interval is used and an interval of +/-$75 is desired, how many cardholders should be sampled?
July 2, 2010 by Angela

Statistics
Sorry to ask another question but I keep struggling with this class. If all else remains the same, which of these will make a confidence interval for a proportion narrower? I. Increase the confidence level. II. Increase the sample size. III. Increase the margin of error. A. I ...
March 29, 2014 by John

Statistics
A city ballot includes a local initiative that would legalize gambling. The issue is hotly contested, and two groups decide to conduct polls to predict the outcome. The local newspaper finds that 53% of 1200 randomly selected voters plan to vote "yes," while a college ...
October 28, 2013 by Jeffrey

Statistics-Confidence Interval
Can someone please help me on how to work this out?? I'm so super confused. Thanks! A professor at Kaplan University claims that the average age of all Kaplan students is 36 years old. Use a 95% confidence interval to test the professor's claim. Is the professor's claim ...
January 16, 2012 by Sara

statistics
Confidence Intervals; In a survey of 1004 individuals, 442 felt that Randolph spent too much time away. Find a 95% confidence interval for the true population proportion
March 25, 2013 by ann

Statistics
A survey organization takes a simple random sample of 625 households from a city of 80,000 households. On the average, there are 2.30 persons per sample household, and the SD is 1.75. Say whether each of the following statements are True or false and explain (a) The SE for the...
October 26, 2011 by Joyann

statistics
how do you get thesampling and confidence intervals for this problem sample scores of 1,2,3,4,5 and 95 percent confidence interval about the sample mean
October 15, 2010 by Inez

statistics
A sample of 134 golfers showed that their average score on a particular golf course was 87.43 with a standard deviation of 4.53. Answer each of the following (show all work and state the final answer to at least two decimal places.): (A) Find the 99% confidence interval of the...
November 2, 2010 by Valerie

statistics
A sample of 106 golfers showed that their average score on a particular golf course was 87.98 with a standard deviation of 5.39. Answer each of the following (show all work and state the final answer to at least two decimal places.): (A) Find the 90% confidence interval of the...
September 2, 2011 by Laynette

statistics
An experimental egg farm is raising chickens to produce low cholesterol eggs. A lab tested 12 randomly selected eggs and found that the mean amount of cholesterol was x = 186 mg. The sample standard deviation was found to be s = 19.0 mg on this group. Assume that the ...
April 6, 2010 by looking for someone to varify my work please

Math/Statistics
Can anyone please help me explain confidence intervals. How does one tell/determine if a confidence interval is too wide? What indicates too wide? Thanks in advance!
October 2, 2012 by Rory

Statistics
What is the appropriate sample size for a confidence interval around the sample mean if you want a margin of error of 0.8 with 95% confidence and a population standard deviation of 12.
November 30, 2012 by Parul

statistics
sing the 95% confidence level and the 11th grade male writing scores in the Class Data file, you would expect the lower end of the confidence interval to be approximately what value?" Answer
November 26, 2012 by Anonymous

Statistics
In a survey of 633 males ages 18-64, 395 say they have gone to the dentist in the past year. Construct 90% and 95% confidence intervals for the population proportion. Interpret the results and compare the widths of the confidence intervals. The 90% confidence interval for the ...
June 10, 2012 by Anonymous

STATISTICS
Bacterial samples were taken from several surfaces in a daycare and incubated in petri dishes. After that the number of bateria colonies were counted, with the following results 412, 437, 425, 476, 451, 483. 1) construct a 95% confidence interval for the mean number of ...
October 11, 2007 by Keirson

statistics
In a sample of 200 people, 154 said they watched educational television. Find the 90% confidence interval of the true proportion of people who watch educational television. If the television company wanted to publicize the proportion of viewers, do you think it should use the ...
November 23, 2012 by Tessa

statistics
1. The new Twinkle bulb has a standard deviation σ = 34 hours. A random sample of 77 light bulbs is selected from inventory. The sample mean was found to be x= 492 hours. Question: Find the margin of error E for a 90% confidence interval. Round your answer to the nearest ...
April 6, 2010 by looking for someone to varify my work please

RES 341
A sample of 300 is taken and the sample mean is computed to be 7.65 and the sample standard deviation is 5. Assume the data is ratio level. Compute the 95% confidence interval on the mean. Compute the 3.9% confidence interval on the mean Which confidence interval is more ...
October 16, 2010 by Meh

Statistics
An opinion poll asks a random sample of 100 college seniors how they view their job prospects. In all, 53 say "Good." The 95% confidence interval has a margin of error of 9.9%. The sample used actually included 130 college seniors but 30 of the seniors refused to answer. This ...
November 11, 2013 by Samantha

statistics
Lorraine was in a hurry when she computed a confidence interval for . Because was not known, she used a Student's t distribution. However, she accidentally used degrees of freedom n + 1 instead of n - 1. v Will her confidence interval be longer or shorter than one found using ...
April 29, 2012 by trina

STATISTICS
Which of the following would increase the width of a confidence interval? Changing from a 99% to 95% confidence level. Increasing the variability of the outcome. Increasing the sample size. Removing an outlier from the data
August 6, 2013 by Susie

STATISTICS
Which of the following would increase the width of a confidence interval? Changing from a 99% to 95% confidence level. Increasing the variability of the outcome. Increasing the sample size. Removing an outlier from the data
August 7, 2013 by Susie

statistics
A consumer magazine has contacted a simple random sample of 33 owners of a certain model of automobile and asked each owner how many defects had to be corrected with in the first 2 months of ownership. The average number of defects was x with (with line over the x)=3.7, with a...
October 15, 2009 by Tammy

statistics
Use the given confidence level and sample data to find a confidence interval for the population standard sigma. Assume that a simple random sample has been selected from a population that has a normal distribution. salaries of college graduates who took a geology course in ...
December 29, 2011 by rich

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