Friday

January 30, 2015

January 30, 2015

Number of results: 23,234

**Statistics: Sample Size, Variance and Standard Dev**

Sample Size, Variance and Standard Deviation A student organization plans to ask 100 randomly selected students how much they spent on textbooks last semester. You argue for a sample of 900 students instead of 100. You know the standard deviation of the sample mean x of the ...
*September 11, 2007 by Carma*

**Statistics**

two samples of data regarding salary of Co A and Co B determine if you can be 99% sure that Co? A makes more than Co B? Company A - Mean 55,000, Std Dev 5,000, Sample Size 200; Co B mean 52,000, Std Dev 3,000 Sample size 400 please show steps thanks
*April 23, 2012 by stylists*

**Statistics**

A normal population has an expected value of 60 and a variance of 30. Use the central limit theorem to determine what the sample size should be such that the mean has a probability of 90% to fall between the values 58 and 62. One concept of the Central Limit Theorem is ...
*August 10, 2006 by ruth*

**Statistics**

Suppose that the fit to the simple linear regression of Y on X from 6 observations produces the following residuals: -3.3, 2.1, -4.0, -1.5, 5.1, 1.6. a) What is the estimate of sigma squared? b) What is the estimate of sigma? c) What are the degrees of freedom? Sigma = ...
*March 14, 2007 by MMK*

**Research and Statistics**

What factors influence the size of the t-statistics( mean difference, variance, sample size) and which way?
*February 10, 2014 by Erica*

**Statistics**

Are these statements true or false? 1. The sample mean, the sample proportion and the sample standard deviation are all unbiased estimators of the corresponding population parameters. 2. If the population is normally distributed with known variance then the sample mean may not...
*November 5, 2010 by help*

**statistics**

An IQ is designed so that the mean is 100 and the standard deviation is 23 for the population of Normal adults, find the sample size necessary to estimate the mean IQ score of statistics students Such that it can be said with 90% confidence that the sample mean is within 5 IQ ...
*May 19, 2014 by joe*

**statistics**

Assuming that the population variances are equal for Male and Female GPAs, test the following sample data to see if Male and Female PhD candidate GPAs (Means) are equal. Conduct a two-tail hypothesis test at =.01 to determine whether the sample means are different. Do NOT ...
*October 6, 2010 by Anonymous*

**Statistics**

An IQ test is designed so that the mean is 100 and the standard deviation is 19 for the population of normal adults. Find the sample size necessary to estimate the mean IQ score of statistics students such that it can be said with 95% confidence that the sample mean is within ...
*February 12, 2014 by Stephanie*

**Statistics**

SAT scores are normally distributed with a mean of 500 and a standard deviation of 100. Using the formula for σM, what will σM be when a. the sample size is 25 b. the sample size is 121, and c. the sample size is 400?
*November 18, 2013 by Mikos*

**economatrics**

calculate standard error when sample size is 25, sample mean is 20, sample variance is 8, population mean is 22, population variance is 64
*November 20, 2014 by priym*

**statistics**

Lets assume you have taken 100 samples of size 36 each from a normally distributed population. Calculate the standard deviation of the sample means if the populations variance is 25.
*June 13, 2010 by Anonymous*

**Quantitative Analysis**

The "standard deviation of the sample score" divided by the "square root of the sample size" is the formula for computing the ...? A. Coefficiant of Determination B. Absolute Deviation C. Variance D. Standard Error
*November 6, 2013 by Stacie*

**statistics**

Suppose we take a random sample of size n from a normal population with variance, σ2 . It can be shown that (n−1)s2/σ2 has a chi-square distribution with n−1 degrees of freedom, where s is the sample variance. Below is a random sample of size 8 drawn from...
*March 18, 2013 by sandy*

**statistics**

IQ scores are normally distributed with a mean of 105 and a standard deviation of 18. Assume that many samples of size n are taken form a large population of people and the mean IQ score is computed for each sample. If the sample size is n=64, find the mean and standard ...
*September 13, 2012 by kimberly*

**statistics**

A researcher is testing a null hypothesis that states: H: = 50. A sample of 25 scores is selected and the mean is M = 55.Assuming that the sample variance is s2 = 100, compute the estimated standard error and the t statistic. Is this sample sufficient to reject the null ...
*April 15, 2011 by kesha*

**Math Statistics**

In general, what is the relationship between the standard deviation and variance? a. Standard deviation equals the squared variance. b. Variance is the square root of standard deviation. c. Standard deviation is the square root of variance. d. These two measures are unrelated.
*September 29, 2012 by Misty*

**statistics**

what are the mean and standard deviation of a sampling distribution consisting of samples of size 16? these sameples were drawn from a population whose mean is 25 and who standard deviation is 5. a. 25 and 1.25 b. 5 and 5 c. 25 and 5 d. 5 and 1.25 e. 25 and square root of 5 ...
*February 1, 2009 by helga*

**Statistics **

1.A sample of 25 bottles is taken from the production line at a local bottling plant. Assume that the fill amounts follow a normal distribution. The probability is 90% that the sample variance is less than what percent of the population variance? 2. The amount of money spent ...
*December 3, 2014 by abidjan*

**Math**

You want to estimate the mean amount spent by customers at a local gas station with 98% confidence and a margin of error of no more than $2. Preliminary data suggests that the standard dev. is $5.1 is a reasonable estimate for the standard dev. for all customers. How large a ...
*February 19, 2011 by Leah*

**statistics**

A psychologist wants to estimate the variance of employee test scores. A random sample of 18 scores had a sample standard deviation 10.4. Find a 90% confidence 2 interval for the population variance. What assumption, if any, have you made in calculating this interval estimate?
*November 9, 2011 by Janelle*

**Statistics**

Check my answers please! Thanks a lot. Five students reported that the previous night they slept: 7,8,7,10,9 hours. Calculate the sample varience and standard deviation. sample varience = 1346.5 standard deviation = 36.7 Consider this. Ths standard deviation can never be ...
*February 1, 2007 by Jake*

**statistics**

You want to determine if your widgets from machine 1 are the same as machine 2. Machine 1 has a sample mean of 5 and a population standard deviation 1 and a sample size of 4. Machine 2 has a sample mean of 8 and a population standard deviation of 2 with a sample size of 4. ...
*October 11, 2010 by Anonymous*

**statistics**

What formula do I use to solve: A sample with a mean of M = 40 and a variance of s2 = 20 has an estimated standard error of 2 points. How many scores are in the sample?
*July 8, 2014 by brenda*

**statistics**

A random sample of n=16 scores is obtained from a population with a mean of = 80 and a treatment is administered to the sample. After treatment, the sample mean is found to be M=82. a)Assuming the sample contained n=16 individuals, measure the size of the treatment effect by ...
*March 5, 2008 by Laurie*

**statistic**

. For each of the following, assume that the two samples are selected from populations with equal means and calculate how much difference should be expected, on average, between the two sample means. a. Each sample has n _ 5 scores with s2 _ 38 for the first sample and s2 _ 42...
*November 11, 2012 by Sharon*

**Stats**

A simple random sample will be obtained from a normally distributed population. Find the minimum sample size needed to be 99% confident that the sample standard deviation s is within 5% of the standard deviation. Is such a sample size practical in most cases? The minimum ...
*November 28, 2011 by Lindsey*

**Statistics**

Use a x squared-test to test the claim about the population variance or standard deviation at the given level of significance and using the given sample statistics. Claim: ơ2 ≤ 60; α = 0.025. Sample statistics: s2 = 72.7, n = 15
*December 26, 2007 by Brandon*

**Statistics**

Use a chi-squared test to test the claim about the population variance or standard deviation at the given level of significance and using the given sample statistics. Claim: ơ2 ≤ 60; α = 0.025. Sample statistics: s2 = 72.7, n = 15
*December 27, 2007 by Brandon*

**Statistics**

The grades in the final exam of a random sample of 25 students produce a standard deviation, s = 9.5. a) Construct a 90% confidence interval estimate for the population variance, . b) Can we infer at 10% level of significance that the population variance is significantly ...
*November 25, 2014 by Kendra*

**business statistics**

A random sample of size 15 taken from a normally distributed population reveled a sample mean of 75 and a sample variance of 25. The upper limit of a 95% confidence interval for the population mean would equal?
*August 1, 2009 by Samantta*

**statistics**

if a sample of a distribution of sample size 26 has a range of 56, then what would be an estimate of the sample standard deviation
*February 14, 2013 by karen*

**Statistics**

There are 200 students in a sample. How many of these students will have scores that fall under the score of 41? Mean is 45, standard dev. is 4.
*November 15, 2011 by Vicki*

**statistics **

Info given:With a random sample of 9 men. let X denote the number of men with head circumference larger than 57.8cm. the normal mean=56cm and standard dev=1.8cm. So this is a binomal dis- they ask; For X, calculate pr(X=2)? second part, Let X denote the number of men with HC ...
*April 15, 2010 by UPD*

**statistics**

Let X be the average of a sample of size 25 independent normal random variables with mean 0 and variance 1. P[[X<c]=0.5 (a) Determine c such that (b) Now assume that the observations may not be normally distributed, but they still are independent with mean 0 and variance 1...
*November 23, 2011 by zwesko*

**Statistics**

2. Obtain and interpret descriptive statistics (Mean, Median, Variance, and Std. Dev.). Include the STATA outputs in your results. (Use Stat command tabstat crimerat police59, statistics(mean, p50, var, sd) (3 pts) . tabstat crimerat police59,statistics (mean, p50, var, sd) ...
*November 8, 2011 by Mikey*

**math**

A sample of size 100 is taken resulting in a standard deviation of 3. Construct a 95% confidence interval for the population variance.
*May 8, 2013 by Jewelz*

**statistics**

Determine the 90% confidence interval for a sample, taken from a normally distributed population, that has a mean of 685, a sample standard deviation of 74, and a sample size of 29
*November 1, 2011 by Tierra*

**statistics**

Determine the 90% confidence interval for a sample, taken from a normally distributed population, that has a mean of 685, a sample standard deviation of 74, and a sample size of 29
*November 1, 2011 by Tierra*

**Statistics**

find the 90% confidence interval for the variance and standard deviation of a sample of 16 and a standard deviation of 2.1 Assume the variable is normally distributed.
*October 24, 2010 by Anon*

**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 ...
*December 1, 2011 by ut*

**Statistics**

Suppose that a sample of size 60 is drawn from a population with mean 73 and standard deviation 79. Find the value of , the standard deviation of the distribution of sample means. How do I work this on my calculator?
*June 18, 2013 by Anonymous*

**Statistics**

If the population is normally distribution then the sample must be normally distributed even for small sample size? True or False. The variance of the standard normal distribution is always equal to 1.? True or False. A continuous random variable may not be normally ...
*February 7, 2014 by Jamie*

**STATISTICS**

According to the Central Limit Theorem, The traditional sample size that separates a large sample size from a small sample size is one that is greater than 100 30 500 20
*June 10, 2010 by John*

**STATISTICS**

WHAT DOES THE CENTRAL LIMIT THEOREM SAY ABOUT THE TRADITIONAL SAMPLE SIZE THAT SEPARATES A LARGE SAMPLE SIZE FROM A SMALL SAMPLE SIZE?
*July 18, 2013 by LINDA*

**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**

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 ...
*December 1, 2011 by Nasir*

**statistics college**

find the range standard deviation and variance for following sample data 2,11,81,29,22,59,78,71,21,43,99,12,38,74,56,81
*May 22, 2012 by melba*

**statistics**

Calculate the variance version of standard error for each sample in Exercise 10.18for the liberals (2, 1, 3, 2) and then for the conservatives (4, 3, 3, 5, 2, 4).
*September 26, 2012 by susan*

**statistics**

How is the standard error of the mean influenced by sample size and standard deviation?
*October 6, 2012 by Nina*

**statistics**

a simple random sample will be obtained from a normally distributed population. find the minimum sample size needed to be 95% confident that the sample standard deviation (s) is within 10% of sigma. please help!
*April 16, 2011 by lucy*

**statistics**

Given a sample size of 38, with sample mean 660.3 and sample standard deviation 95.9 we are to perform the following hypothesis test. Null Hypothesis H0: = 700 Alternative Hypothesis H0: 700 At significance level 0.05 3. Calculate the test statistics (Tip: this is the...
*August 9, 2010 by Scott*

**STAT**

You want to determine if your widgets from machine 1 are the same as machine 2. Machine 1 has a sample mean of 15 and a sample standard deviation 6 and a sample size of 18. Machine 2 has a sample mean of 12 and a sample standard deviation of 6 with a sample size of 18. With an...
*October 4, 2013 by Tammy*

**statistics 251**

how do i find the standard deviation and sample variance for $7448, $4911, $9051, $6374, $4227
*September 13, 2012 by amirah*

**Statistics**

Kind attention Psydag: A random sample of size 20 from a normal population with sample mean 42 and sample standard deviation of 6 . To test the hypothesis the population mean 44 at 5% level of significance , find the p-value and comment Clarification: The sample size is 20 ...
*January 1, 2010 by Mrs. Lakshmi*

**Statistics**

The table below shows the LOS for a sample of 11 discharged patients. Using the data in the table, calculate the mean, range, variance, and standard deviation, and then answer questions e and f. Round the variance and standard deviation to one decimal place. a. Mean b. Range ...
*November 11, 2013 by Anonymous 11/11/13*

**Statistics**

IQ score are normally distributed with a mean of 95 and a standard deviation of 17. If the sample size is n=36 find the mean and standard distribution of sample mean
*April 7, 2013 by Megan*

**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 ...
*May 6, 2014 by Mia*

**Statistics**

A sample of 12 measurements has a mean of 37 and a standard deviation of 4.25. Suppose that the sample is enlarged to 14 measurements, by including two additional measurements having a common value of 37 each. A. Find the mean of the sample of 14 measurements. Mean = 37 How I ...
*September 4, 2014 by Anonymous*

**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). ...
*April 14, 2014 by Vanessa*

**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). ...
*April 15, 2014 by Vanessa*

**Sampling Distribution**

Sampling Distribution Complete solutions and illustrations are required. 5.The standard deviation of a variable is 15. If a sample of 100 individuals are selected compute for a.The standard error of the mean. b.What sample size is necessary to double the standard error of the ...
*February 27, 2013 by Tina*

**statistics**

A 95% confidence interval for a population mean was reported to be 23,100 to 24,900. If the sample standard deviation is 5,808.26, what sample size was used in this study?
*June 5, 2011 by Anige*

**Statistics**

A 82% confidence interval for a sampling distribution with a mean of 100, a sample standard deviation of 24 and a sample size of 36 will be based on a = ______ and a corresponding Z of ___
*March 5, 2012 by Jeff*

**Statistics**

A 82% confidence interval for a sampling distribution with a mean of 100, a sample standard deviation of 24 and a sample size of 36 will be based on a = ______ and a corresponding Z of ___
*March 5, 2012 by Jeff*

**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 ...
*July 16, 2012 by Devika*

**statistics**

sigma is the standard deviation of a population of size N S is the standard deviation of a sample of size n from within the population. What is the estimated value of S^2? If the population was infinitely large (size N = infinity), what would the estimated value of S^2 be?
*February 21, 2008 by mathstudent*

**elementary statistics**

A statistics professor is used to having a variance in his class grades of no more than 100. He feels that his current group of students is different, and so he examines a random sample of midterm grades (listed below). At 0.05 alpha level can it be conculded that the variance...
*November 30, 2013 by David*

**elementary statistics**

A statistics professor is used to having a variance in his class grades of no more than 100. He feels that his current group of students is different, and so he examines a random sample of midterm grades (listed below). At 0.05 alpha level can it be conculded that the variance...
*November 30, 2013 by David*

**statistics**

A population has a mean =80 and a standard deviation =8. find the mean and standard deviation of a sampling distribution of sample means with sample size=64
*February 12, 2013 by antorio*

**Statistics **

The table below shows the LOS for a sample of 11 discharged patients. Using the data in the table, calculate the mean, range, variance, and standard deviation, and then answer questions e and f. Round the variance and standard deviation to one decimal place. a. Mean b. Range c...
*November 9, 2013 by Anonymous 11/9/13*

**college math**

20. Calculate the range, variance, and standard deviation of the following data set: 5, 5, 6, 6, 6, 8, 8, 8, 8, 10, 10, 11, 12, 12, 20 (Points: 5) Range = 15; Variance = 225; Standard Deviation = 7.5 Range = 3.85; Variance = 14; Standard Deviation = 3.74 Range = 20; Variance...
*November 7, 2011 by Anonymous*

**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 ...
*November 6, 2008 by Marshall*

**Statistics**

find the 90% confidence interval for the variance and standard deviation of the ages of seniors at Oak Park College if a sample of 24 students has a standard deviation of 2.3 years. Assume the variable is normally distributed. Can someone explain the steps to solve this? ...
*October 26, 2010 by Diandra*

**Statistics**

For sample mean x = 150, sample size n = 36 and sample standard deviation s = 40 find 80% confidence interval for population mean. Population standard deviation is not known
*February 24, 2012 by Tina*

**statistics**

1. A random sample of size 49 is taken from a large population, measuring the time it takes to complete a drivers license examination. The sample mean was found to be 47 minutes, and the sample standard deviation 5.89 minutes. Construct a 95% confidence interval around the ...
*July 16, 2010 by Anonymous*

**statistics**

A random sample of size 81 is taken from a large population, measuring the time it takes to complete a drivers license examination. The sample mean was found to be 43 minutes, and the sample standard deviation 5.71 minutes. Construct a 95% confidence interval around the ...
*July 16, 2012 by Devika*

**business statistics**

A 82% confidence interval for a sampling distribution with a mean of 100, a sample standard deviation of 24 and a sample size of 36 will be based on a = ______ and a corresponding Z of ____ .18 and .47 .18 and .915. .09 and .23 .09 and 1.34
*July 11, 2011 by CS*

**statistics**

For normal population mean 60, standard deviation 15, after treatment is given to the member of sample , the sample mean is 65, and sample size is 25. is the sample mean sufficient to conclude that the treatment has significant effect? Give reason for decision?
*August 11, 2012 by Anonymous*

**statistics**

Scores on a certain test are normally distributed with a variance of 14. A researcher wishes to estimate the mean score achieved by all adults on the test. Find the sample size needed to assure with 95% confidence that the sample mean will not differ from the population mean ...
*September 13, 2010 by Sarah*

**Statistics**

Data Set A: Average = $157 Standard Dev. = $84 Data Set B: Average = 34 oz. Standard Dev. = 21 oz Which Data Set is more variable?
*October 20, 2014 by diva24*

**statistics**

Scores on a certain test are normally distributed with a variance of 91. A researcher wishes to estimate the mean score achieved by all adults on the test. Find the sample size needed to assure with 95.44 percent confidence that the sample mean will not differ from the ...
*June 25, 2011 by vina*

**statistics**

A standard IQ test has a mean of 98 and a standard deviation of 16. We want to be 90% certain that we are within 8 IQ points of the true mean. Determine the sample size.
*December 8, 2011 by kat*

**statistics**

population has mean 53 and standard deviation 12. Calculate the standard deviation of x bar for a random sample of size 12.
*August 18, 2014 by Bridget*

**Statistics**

A random sample of size 20 from a normal population will sample mean 42 and sample standard deviation of 6 . To test the hypothesis the population mean 44 at 5% level of significance , find the p-value and comment
*December 31, 2009 by Mrs. Lakshmi*

**statistics**

A random sample of size 20 from a normal population will sample mean 42 and sample standard deviation of 6 . To test the hypothesis the population mean 44 at 5% level of significance , find the p-value and comment
*June 3, 2010 by masood*

**Statistics**

data from sample of 400 cases, variable has 95% confidence interval of 54.3 to 54.7 I found the mean- how do i find standard error- step by step please. Standard error = sd/√n Note: sd = standard deviation; n = sample size. You'll need to determine the standard deviation...
*April 10, 2007 by Angel*

**Business Statistics**

The standard deviation of all possible sample proportions increases as the sample size increases - TRUE OR FALSE
*July 11, 2011 by CS*

**statistics**

ER promises you will be seen in 10 minutes. the standard deviation is 2 minutes. chance someone will wait more than 13 minutes. i dont know what to do without a population size or sample size
*April 3, 2013 by K*

**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**

Calculate SS, variance, and standard deviation for the following sample of n _ 4 scores: 3, 1, 1, 1. (Note: The computational formula works well with these scores.)
*June 22, 2011 by Liz *

**statistics**

Group the largest data set and find mean, median, mode, variance, standard deviation, 15-th, 45-th and 80-th percentiles of the grouped data. Then find the same sample statistics using the ungrouped data. Is there any difference? Comment.
*November 20, 2011 by metu*

**statistics**

In an extensive study involving thousands of British children, Arden and Plomin (2006) found significantly higher variance in the intelligence scores for males than for females. Following are hypothetical data, similar to the results obtained in the study. Note that the scores...
*June 22, 2011 by Liz *

**Statistics**

. A random sample is selected from a normal population with a mean of __40 and a standard deviation of __10. After a treatment is administered to the individuals in the sample, the sample mean is found to be M _ 42. a. How large a sample is necessary for this sample mean to be...
*January 26, 2012 by Sharon*

**econ 2110**

Suppose that we want to test whether the mean selling price of houses with is the same as the mean selling price of houses without a garage. We collect two samples and obtain the following information: Houses with garage Sample size: 71 Mean selling price (in thousands of ...
*September 19, 2014 by katlyn*

**statistics**

Determine the sample size required to estimate a population proportion to within 0.032 with 95.7% confidence, assuming that you have no knowledge of the approximate value of the sample proportion. Sample Size = B. Repeat part the previous problem, but now with the knowledge ...
*March 28, 2009 by Joey*

**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**

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?
*February 20, 2014 by Keith*

**statistics**

An SRS of size n is taken from a large population whose distribution of income is extremely right-skewed and the mean income is calculated. Which of the following statements is false? a) When n > 30, the sampling distribution of is approximately normal. b) When n increases...
*April 17, 2012 by Anna*

**STAT**

You want to determine if your widgets from machine 1 are the same as machine 2. Machine 1 has a sample mean of 5 and a population standard deviation 2 and a sample size of 4. Machine 2 has a sample mean of 10 and a population standard deviation of 2 with a sample size of 64. ...
*October 7, 2013 by Tammy*

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