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No. & Date AskedQuestion
# 945 :: 4/29/12
Question 945 has been Answered
In a survey of 1000 electors, 20% were found to favour party "stats". 1. Construct a 95% C.I for the percentagew in favour of party "stats". 2. What. . .

Confidence Intervals, Sample Size

# 944 :: 4/29/12
Question 944 has been Answered
Mr. price Home analyzed the value of purchase made on credit by a sample of 25 credit card customers. The simple mean was found to be R170.08 with a s. . .

Confidence Intervals

# 915 :: 12/6/11
Question 915 has been Answered
create a 95%confidence interval for the value of the population mean, given that their is a sample mean of 49 and a standard deviation of 3 but now fo. . .

1-sample t-test, Confidence Intervals

# 914 :: 12/6/11
Question 914 has been Answered
create a 95% confidence interval for the value of the population mean, given that their are 64 observations and a sample mean of 49, with a sample sta. . .

1-sample t-test, Confidence Intervals

# 905 :: 12/3/11
Question 905 has been Answered
create a 95% confidence interval for the value of the population mean using the following information: a sample mean of 55, a sample standard deviatio. . .

Confidence Intervals

# 893 :: 7/12/11
Question 893 has been Answered
Elbow to fingertip length of men 99% confidence n=32, x- 14.50,s= 0.70 what is the margin of error. . .

Margin of Error, Confidence Intervals

# 868 :: 10/14/10
Question 868 has been Answered
Suppose that a 90% confidence interval for a population mean μ is constructed from a sample, resulting in the interval from 120 to 150. What was. . .

Confidence Intervals, Margin of Error

# 860 :: 3/30/10
Question 860 has been Answered
Problem # 1: Clothing for Runners: Your company sells exercise clothing and equipment on the internet. To design the clothing, you collect a data on. . .

Confidence Intervals, Margin of Error

# 859 :: 3/18/10
Question 859 has been Answered
1) Spinifex pigeons are one of the few bird species that inhabit the desert of Western Australia. The pigeons rely almost entirely on seeds for food. . . .

Confidence Intervals

# 775 :: 7/6/09
Question 775 has been Answered
1.-A state meat inspector in Iowa has been given the assignment of estimating the mean net weight of packages of ground chuck labeled ď3 pounds.Ē Of c. . .

Confidence Intervals

# 735 :: 5/25/09
Question 735 has been Answered
how does a confidence interval this relate to learning statistics How do you think confidence intervals are useful in the real-world?. . .

Confidence Intervals

# 703 :: 4/26/09
Question 703 has been Answered
The following data is a random sample of 1st quiz scores from previous Research 342 classes. 9.5, 6.5, 4.25, 8.5, 7.5, 4.5, 4.25, 6, 7 mean = 6.44 . . .

Confidence Intervals

# 684 :: 4/18/09
Question 684 has been Answered
Tax companies imply that the returns they prepare are perfect, but what proportion of returns from tax companies have mistakes? To answer this questio. . .

Confidence Intervals, Confidence Interval around a Proportion

# 683 :: 4/18/09
Question 683 has been Answered
A baseball fan would like to estimate the mean time it takes to complete a major league baseball game. He randomly selects 40 game lengths (times to c. . .

Confidence Intervals

# 637 :: 2/22/09
Question 637 has been Answered
Hi Jeff thanks for all your help so far, your answers have been great and very timely. It is great to be able have help from someone with great profes. . .

Adjusted Wald, Confidence Intervals

# 635 :: 2/22/09
Question 635 has been Answered
Linemarking for parking bays shall be determined by the retroreflectivity performance of glass beads in the linemarking. The linemarking average level. . .

1-sample t-test, Confidence Intervals

# 557 :: 12/16/08
Question 557 has been Answered
Find the margin or error for the 95% confidence interval used to estimate the population proportion. In a survey of 7100 TV viewers, 38% said they wa. . .

Confidence Intervals, Margin of Error

# 551 :: 12/12/08
Question 551 has been Answered
Philadelphia is conducting a study on the characteristics of tourists who drive to Eagles football games. Previous studies indicate that approximately. . .

Sample Size, Confidence Intervals, Proportion

# 523 :: 11/24/08
Question 523 has been Answered
Use the given degree of confidence and sample data to construct a confidence interval for the population mean x. Assume that the population has a norm. . .

Confidence Intervals, TINV

# 521 :: 11/24/08
Question 521 has been Answered
The width of a confidence estimate for a proportion will be: a. Narrower for a 99% confidence interval than for a 95% confidence interval. b. Wider . . .

Confidence Level, Confidence Intervals, Proportion

# 520 :: 11/23/08
Question 520 has been Answered
Your company asks you to compare a new advertising campaign and the old one. Sample data on the accounts as follows: Old: 40, 28, 35, 38, 31, 42, 26,. . .

Confidence Intervals, Median, Mode, mean, t-statistic, Standard Error of the Mean

# 511 :: 11/13/08
Question 511 has been Answered
A machine produces 3 inch nails. A sample of 100 nails is selected, and it is found that 25 are shorter than 3 inches. Find the 95% confidence interv. . .

Proportion, Confidence Intervals, One-Tailed Area

# 509 :: 11/13/08
Question 509 has been Answered
A researcher expects the population proportion of the Cubs Fans in Chicago to be 80%. Error of less than 5% confident of an estimate to be made from a. . .

Confidence Intervals, Sample Size, Margin of Error

# 507 :: 11/12/08
Question 507 has been Answered
In a survey of 500, 60% responded positively to an value question. Calculate a confidence level at 95% to get an interval estimate for proportion?. . .

Sample Size, Confidence Intervals, Proportion

# 506 :: 11/12/08
Question 506 has been Answered
Suppose you are planning a sample of employees to determine the monthly average # of vacation days. Standards set: Confidence level of 99% and an erro. . .

Sample Size, Margin of Error, Confidence Intervals

# 505 :: 11/11/08
Question 505 has been Answered
Calculate a 98% confidence interval for the following data 15.7,15.7,15.5,15.2,15.2,15.1,15.3.. . .

Confidence Intervals, TINV, Margin of Error, t-statistic

# 504 :: 11/9/08
Question 504 has been Answered
Calculate the 95% confidence interval on the following GPA's from 30 randomly selected students. 0.979 0.891 0.962 0.858 0.909 0.936 0.963 0.9. . .

Confidence Intervals, Margin of Error, t-statistic

# 502 :: 11/7/08
Question 502 has been Answered
Administrative staff based at a business school in the UK are advised to take a 15 minute break from their personal computer after working on it for 9. . .

Confidence Intervals, TDIST, t-test, Z-Score

# 497 :: 11/6/08
Question 497 has been Answered
A random sample of n=64 children of working mothers showed that they were absent from school an average of 5.3 days per term, with a standard deviatio. . .

Confidence Intervals, Confidence Level

# 487 :: 10/28/08
Question 487 has been Answered
Find a confidence interval for the mean assuming that each sample is from a normal population. Mean = 127, s = 27, n = 16. Find the 90% Confidence Int. . .

TINV, t-distribution, Confidence Intervals

# 485 :: 10/27/08
Question 485 has been Answered
Assume that the heights of 5 year old boys are normally distribued with a mean of 100cm and a standard deviation of 60. What is the sampling distribut. . .

TINV, Confidence Intervals, Standard Error of the Mean, Standard Deviation of the Mean

# 471 :: 10/9/08
Question 471 has been Answered
A central university has a student population of 60,000. The university is interested in determining what proportion of them is in favour of a new gra. . .

Margin of Error, Confidence Intervals, Sample Size

# 470 :: 10/9/08
Question 470 has been Answered
A telescope manufacturer wants its telescopes to have standard deviations in resolution to be significantly below 2 when focusing on objects 500 light. . .

Chi-Square Distribution, Confidence Intervals, Standard Deviation, Variance

# 458 :: 10/5/08
Question 458 has been Answered
In 1992, the FAA conducted 86,991 pre-employment drug tests on job applicants who were to be engaged in safety and security-related jobs, and found th. . .

Confidence Intervals, Normality Assumption

# 451 :: 10/3/08
Question 451 has been Answered
A sample of the math test scores of 35 fourth-graders has a mean of 82 with a standard deviation of 15. Find the 95% confidence interval of the mean. . .

Confidence Intervals, Confidence Level

# 403 :: 9/22/08
Question 403 has been Answered
Based on information obtained from a sample of 54, a 98% confidence interval for the average profit level of regional banks is given by 67.4 million t. . .

Standard Deviation, Margin of Error, Critical Value, Confidence Intervals, Confidence Level

# 402 :: 9/21/08
Question 402 has been Answered
How can I compute a one-sided 97.5% confidence interval using SPSS for this ? IN a cohort of 121 eyes treated with drug A, 3 eyes experience a drug . . .

SPSS, Confidence Intervals, 1-sided Interval

# 391 :: 9/18/08
Question 391 has been Answered
An engineer in an automotive factory wishes to know what the tire pressure is on all cars leaving the factory. She measures the tire pressure on a sa. . .

Standard Error of the Mean, t-statistic, Confidence Intervals, Critical Value

# 383 :: 9/15/08
Question 383 has been Answered
Briefly describe the concept of a confidence interval and provide an example.. . .

Confidence Intervals

# 369 :: 9/5/08
Question 369 has been Answered
A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on very accurate scale. The results in grams were 3.087 3.. . .

Margin of Error, Sample Size, Confidence Intervals

# 364 :: 9/4/08
Question 364 has been Answered
A sample of 20 pages was taken without replacement from the 1,591-page phone directory Ameritech Pages Plus Yellow Pages. On each page, the mean area . . .

Margin of Error, Confidence Intervals, Sample Size

# 362 :: 9/1/08
Question 362 has been Answered
Popcorn kernels take between 100 and 200 seconds to pop. What sample size (number of kernels) would be needed to estimate the true mean seconds to pop. . .

Small Sample, Sample Size, Margin of Error, Confidence Intervals

# 357 :: 8/25/08
Question 357 has been Answered
Biting an unpopped kernel of popcorn hurts! As an experiment, a self-confessed connoisseur of cheap popcorn carefully counted 773 kernels and put them. . .

Confidence Intervals, Normal Approximation to Binomial , Proportion

# 351 :: 8/17/08
Question 351 has been Answered
As an experiment, a self-confessed connoisseur of cheap popcorn carefully counted 773 kernels and put them in a popper. After popping, the unpopped ke. . .

Confidence Intervals

# 315 :: 8/5/08
Question 315 has been Answered
An engineer in an automotive factory wishes to know what the tire pressure is on all cars leaving the factory. She measures the tire pressure on a sa. . .

Standard Error of the Mean, Standard Deviation, Confidence Intervals, Critical Value, t-statistic

# 278 :: 7/15/08
Question 278 has been Answered
out of a random sample 167 students pass an exam out of the 300. how do you calculate an exact 99% confidence interval for the proportion of sudents w. . .

exact interval, Confidence Intervals

# 263 :: 7/6/08
Question 263 has been Answered
Determine the critical value Za/2 that corresponds to 94% level of confidence Compute the 90% confidence interval about m if the sample size, n, is. . .

Critical Value, Confidence Intervals, Margin of Error

# 247 :: 6/24/08
Question 247 has been Answered
Jeff: Can you possibly share the actual formula you are using in this application to produce the Adjusted Wald calculations? Thanks. . .

Adjusted Wald, Z-Score, Confidence Intervals

# 215 :: 6/3/08
Question 215 has been Answered
Annual starting salaries for college graduates with degrees in business administration are generally expected to be between $30,000 and $45,000. Assum. . .

Standard Normal Curve, Confidence Intervals, Standard Deviation, Normally Distributed

# 214 :: 6/2/08
Question 214 has been Answered
I am charged with sampling expense report submissions for accuracy. We get 8000 T&E claims, and want to sample a subset making inferences about the p. . .

1-sample t-test, Confidence Intervals, Sample Size

# 212 :: 6/1/08
Question 212 has been Answered
How would I figure out a 90% and 95% confidence interval for the below informaion? What would be the formula? Can I figure this out in Excel or Mega. . .

t-distribution, Confidence Intervals, TINV, Margin of Error

# 209 :: 5/29/08
Question 209 has been Answered
In 1992, the FAA conducted 86,991 pre-employment drug tests on job applicants who were to be engaged in safety and security relatd jobs and found that. . .

Central Limit Theorem, binomial, Normal Approximation, Confidence Intervals

# 164 :: 4/23/08
Question 164 has been Answered
how to calculate one sided 95% confidence limits for a proportion.could you provide a formula . . .

Adjusted Wald, Confidence Intervals, One-Tailed Area

# 163 :: 4/22/08
Question 163 has been Answered
When calculating confidence interval estimates...how is the x and standard deviation calculated?. . .

Standard Deviation, Confidence Intervals

# 162 :: 4/22/08
Question 162 has been Answered
I am trying to do A/B testing onweb page displays. One is the test the other is the control. Could you help me determine the formula for sample size . . .

Confidence Intervals, Control Chart, A/B Testing, p-chart

# 160 :: 4/21/08
Question 160 has been Answered
in a sample of 1000 tv vieweres 330 watched a particlar programme. find 99 pecent confidence limits for tv viewers who watched this programme. . .

Confidence Intervals, Adjusted Wald

# 152 :: 4/14/08
Question 152 has been Answered
If 350 respondents out of a random sample of 1,000 Americans reported that they did not trust their government, what is your estimation at a 99% confi. . .

Adjusted Wald, Confidence Intervals

# 151 :: 4/14/08
Question 151 has been Answered
A random sample of 25 households finds that an average of 2.3 people reside in each house (the standard deviation is 0.35). With a 95% confidence lev. . .

TINV, t-statistic, t-distribution, Confidence Intervals, Standard Error of the Mean, Margin of Error

# 128 :: 3/25/08
Question 128 has been Answered
What is the value of z score required for a 70% confidence interval?. . .

Z-Score, , Confidence Intervals

# 58 :: 10/29/07
Question 58 has been Answered
Why don't statisticians calculate 100% confidence intervals?. . .

Confidence Intervals, Confidence Level

# 31 :: 10/29/07
Question 31 has been Answered
What is the Z score of a 98% confidence interval?. . .

Confidence Intervals, Confidence Level