# Statistics: Sample Size, Variance and Standard Dev

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### 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 ...

### 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

### 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 = ...

### 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 ...

### statistics check my work

Use gender to assess if there is any difference in duration of hospital stay based on gender. what is the sample size, mean, standard deviation of the males and females during the 25 days in the hospital (key 1=male, 2= female) Duration ........Gender 5............. 2 10...

### Research and Statistics

What factors influence the size of the t-statistics( mean difference, variance, sample size) and which way?

### 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...

### 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 ...

### 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 ...

### statistics

Assuming that the population variances are equal for Male and Female GPA’s, test the following sample data to see if Male and Female PhD candidate GPA’s (Means) are equal. Conduct a two-tail hypothesis test at á =.01 to determine whether the sample means are different. Do...

### 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 ...

### 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

### statistics

Let’s 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 population’s variance is 25.

### Statistics

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

### statistics check my work..thank you

Use “service” to assess if there is any difference in duration of hospital stay based on what type of service medical or surgical the patient received during the 25 days in hospital (Key medical=1, surgical=2) what is the sample size, mean and standard deviation? Duration ...

### 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

### Statistics

A random sample of size n is to be drawn from a population with a mean = 500 and sd = 100. What sample size would be necessary to ensure a standard error of 25? Sample sizes are whole numbers.

### Statistics

A random sample of size n is to be drawn from a population with a mean = 1100 and SD = 300. What sample size would be necessary to ensure a standard error of 25? Sample sizes are whole numbers.

### Math Statistics

A random sample of size n is to be drawn from a population with a mean = 500 and sd = 100. What sample size would be necessary to ensure a standard error of 25? Sample sizes are whole numbers.

### 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...

### statistics

A simple random sample of a size n is drawn from a population that is normally distributed. The sample mean, x is found to be 110, and the sample standard deviation, s, is found to be 10. A- Construct a 95% confidence interval about u if the sample size, n, is 17

### statistics

A researcher is testing a null hypothesis that states: H: ì = 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 ...

### 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.

### 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 ...

### 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 ...

### 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 ...

### 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 ...

### Statistics

a sample of n=25 scores has a mean of M=65 and an estimated standard error of 2 points. What is the sample variance

### 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?

### 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 ...

### statistics

Q- Two samples of sizes 8 and 10 are drawn from two normally distributed population having variance 20 and 36 respectively. Find the probability that the variance of the first sample is more than twice the variance of the second sample.

### 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?

### 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. ...

### math

two sample of size 8 and 10 are drawn from two normally distributed populations having variances 20 and 36, respectively. find the probability that the variance of the first sample is more than twice the variance of the second sample.

### statistic

Two samples each of size 25 are taken from independent populations assumed to be normally distributed with equal variances. The first sample has a mean of 35.5 and standard deviation of 3.0 while the second sample has a mean of 33.0 and standard deviation of 4.0. The pooled (i...

### statistics

A random sample of n=16 scores is obtained from a population with a mean of µ= 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...

### 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

### 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

### 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...

### 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 ...

### 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 ...

### math

An organizational psychologist measures levels of job satisfaction in a sample of 30 participants. To measure the variance of job satisfaction, it is calculated that the SS = 120 for this sample. What are the degrees of freedom for the variance? Compute the variance and ...

### 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?

### statistics

2. Find the variance and standard deviation of the following sample. 0 -5 -3 6 4 -4 1 -5 0 3

### 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.

### 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, ...

### 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

### 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 ...

### 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...

### statistic

A random sample of size n = 72 is taken from a finite population of size N = 644 with mean μ = 239 and variance σ2 = 325. Use Table 1. a-1. Is it necessary to apply the finite population correction factor? Yes No a-2. Calculate the expected value and the standard ...

### 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

### 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

### math

A sample of size 100 is taken resulting in a standard deviation of 3. Construct a 95% confidence interval for the population variance.

### 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.

### statistics

historically, the average customer spends $8.53 for all TGP restaurants(u=8.53). If the population standard deviation is $1.06(o=1.06) and the data is normally distributed, find the probabiltiy that the sample mean will be within $.15 of the populaiton mean using a sample size...

### 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?

### 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 ...

### 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?

### 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 ...

### Statistics

Assume that the unit of measure for each of the values in the sample is in dollars. What would be the units of measure for the sample: a) mean? b) range? C) Variance? d) Standard deviation?

### 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

### STATISTICS

WHAT DOES THE CENTRAL LIMIT THEOREM SAY ABOUT THE TRADITIONAL SAMPLE SIZE THAT SEPARATES A LARGE SAMPLE SIZE FROM A SMALL SAMPLE SIZE?

### 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

### statistics

Calculate the variance version of standard error for each sample in Exercise 10.18—for the liberals (2, 1, 3, 2) and then for the conservatives (4, 3, 3, 5, 2, 4).

### 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 ...

### statistics

How is the standard error of the mean influenced by sample size and standard deviation?

### 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!

### 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: ƒÊ = 700 Alternative Hypothesis H0: ƒÊ ‚ 700 At significance level 0.05 3. Calculate the test statistics (Tip: this...

### Statistics

Suppose you have a sample of 6 observations from a normal population. The sample variance is equal to 4. Find a 90% lower confidence interval for the variance of the population.

### 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...

### statistics 251

how do i find the standard deviation and sample variance for $7448, $4911, $9051, $6374, $4227

### 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...

### Statistics

According to one pollster, 48% of people are afraid of flying. Suppose that a sample of size 20 is drawn. Find the value of standard error , the standard deviation of the distribution of sample proportions. Write only a number as your answer. Round to two decimal places (for ...

### 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 ...

### 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

### statistics

Select the TWO options that are TRUE statements about two-sample t-tests. Select one or more: The same formula is used for the ESE (estimated standard error) in the two-sample t-test with a common variance and the two-sample t-test with unequal variances. A researcher has ...

### statistics

Select the TWO options that are TRUE statements about two-sample t-tests. Select one or more: The same formula is used for the ESE (estimated standard error) in the two-sample t-test with a common variance and the two-sample t-test with unequal variances. A researcher has ...

### 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 ...

### 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 ...

### 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 ...

### 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 ...

### 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). ...

### 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). ...

### statistics

Given a sample size of 36, with sample mean 400 and sample standard deviation 85, we perform the following hypothesis test, at the 95% level of confidence: Ho: ƒÊ = 450, Ha: ƒÊ ‚ 450. What is the question and what is the answer?

### statistics

x is normally distributed and that sample of 20 yields a mean of 42 and a variance of 25 test the hypothesis that the population standard deviation is 8 at 5% significance level.

### 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...

### 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...

### 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?

### 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 á= ______ and a corresponding Zá of ___

### 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 á= ______ and a corresponding Zá of ___

### 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 ...

### 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...

### 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 ...

### 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

### 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?

### 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...

### 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? ...

### 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 ...

### statistics

1. A random sample of size 49 is taken from a large population, measuring the time it takes to complete a driver’s 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 ...