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April 20, 2014

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Number of results: 16,755

Statistics
I have another Stats question i'm confuesed on. classify the sample as random, systematic, covenience, stratified, or cluster. A marketing executive fo General Motors finds that its public department has just printed envelopes with the names and addresses of all Corvette ...
Monday, January 21, 2013 at 9:14pm by Gavin

alg
Find the sample size that produces the margin of error 3.0%
Monday, May 12, 2008 at 10:09pm by jerson

algebra
Find the sample size that produces the margin of error 3.0%
Monday, May 12, 2008 at 10:54pm by jerson

statistics
Both parts are using one-sample two-tailed tests. Since the sample in part a) is so small, you can try a one-sample t-test and for part b), a one-sample z-test. For the t-test: t-statistic = (sample mean - population mean)/(standard deviation divided by the square root of the ...
Thursday, February 28, 2008 at 1:37am by MathGuru

Maths
A psychological test was given to 92 teenage boys and 68 teenage girls. The test was used to assign a score to each teenager, measured on the worry scale 0 (not worried) to 100 (very worried). A summary of the results is given in the table below. Girls; Sample Size 68 ...
Thursday, May 12, 2011 at 2:44pm by Tony

statistics
Describe the distribution of sample means (shape, expected value, and standard error) for samples of n _ 36 selected from a population with a mean of _ 100 and a standard deviation of _ _ 12. The distribution of sample means is not always a normal distribution. Under what ...
Sunday, June 9, 2013 at 6:09pm by Tami

STATISTICS HELP PLEASE!
suppose you wish to estimate a population mean based on a random sample of n observations, and prior experience suggests that sd=12.7. if you wish to estimate the mean correct to within 1.6, with probability equal to .95, how many observations should be included in your sample?
Monday, November 15, 2010 at 7:46pm by Courtney

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?
Wednesday, November 9, 2011 at 9:21am by Janelle

Math
Having trouble knowing where to start with this one: A maker of tools claims the average amount of time it takes to assemble a table saw is 50 mins with a standard deviation of 40 mins. What is the probability that the sample mean will be less than 44 mins if a random sample ...
Tuesday, March 23, 2010 at 12:28am by Len

statistics
In the U.S. 42% of the population has type A blood. Consider taking a sample size 4. Let y denote the number of persons in the sample with type A blood. a)Pr(y=O) b)Pr(y=1) C)Pr(y=2)
Tuesday, February 5, 2008 at 7:32pm by alice

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 ...
Monday, September 13, 2010 at 7:58pm by Sarah

Statistics
A university has 1,000 computers available for students to use. Each computer has a 250-gigabyte hard drive. The university wants to estimate the space occupied on the hard drives. A random sample of 100 computers showed a mean of 115 gigabytes used with a standard deviation ...
Sunday, October 27, 2013 at 9:30pm by Shelby

stats of biologists
a manufacturer claims that the life time of a certain brand of batteries has a varaince of 5000(hours)^2. a sample of 26 has a variance of 7200(hours)^2. assuming that it is reasonable to treat these data as a random sample from a normal population, test the manufacturer's ...
Thursday, February 14, 2013 at 8:48am by Aboli

Math
Drawing student names from a hat is another good example. Isn't that a simple random sample?
Tuesday, September 2, 2008 at 5:33pm by Ms. Sue

statistics
I truly have never seen a "random" sample. What is .78^10? 0.0833
Sunday, March 13, 2011 at 3:33pm by bobpursley

statistics
If it is truly random, it is likely. What sort of data is she gathering about these movies with her sample?
Thursday, February 2, 2012 at 9:54am by PsyDAG

math
Find the probability between 42 and 48 speeders in a random sample of 100
Thursday, May 2, 2013 at 3:30pm by john jones

statistics
A manufacturer wishes to estimate the reliability (in months) of a certain product. An estimate of the population standard deviation from a previous sample was 12 months. If the manufacturer desires to be within 4 months of the true value with approximately 80% confidence, ...
Tuesday, November 8, 2011 at 11:28am by Larry

stats
An automobile repair shop has determined that the average service time on an automobile is 2 hours with a standard deviation of 32 minutes. A random sample of 64 out of 400 services is selected. What is the probability that this sample will have a mean service time greater ...
Wednesday, November 11, 2009 at 9:43pm by sandy

Stats
Recently, an automobile insurance company performed a study of a random sample of 15 of its customers to determine if there is a positive relationship between the number of miles driven and the age of the driver. The sample correlation coefficient is r=.38. Given this ...
Monday, June 13, 2011 at 4:12pm by Breezy

AP Stats
The mean weight of pears grown in a certain orchard is 6 ounces with a standard deviation of .5 ounces. A random sample of 30 pears is selected. What is the approximate probability that the sample mean weight is less than 5.5 ounces?
Sunday, April 25, 2010 at 9:12pm by Lilly

statistics
How does sample size differ between qualitative and quantitative methods? Why?
Thursday, June 19, 2008 at 5:28pm by nicky

statistics
How does the sample size differ between qualitative and quantitative methods? Why?
Monday, October 20, 2008 at 7:06pm by nicky

statistics
2. How does the sample size differ between qualitative and quantitative methods? Why?
Wednesday, October 22, 2008 at 12:04am by nicky

statistics
If a sample of size 30 is selected, the value of A for the probability p(t A)= 0.01 is?
Saturday, August 1, 2009 at 1:46pm by Lina

Business Statistics
As the sample size increases, the standard deviation decreases.
Monday, July 11, 2011 at 7:47pm by MathGuru

Staitstics
What statistical test would be appropriate for a sample size of 25
Tuesday, November 8, 2011 at 8:31pm by Tommy

Please can you help me (Statistic))
The only thing I can think of is increasing the size of the sample.
Sunday, May 13, 2012 at 10:32am by PsyDAG

statistics
90% confidence; the sample size is 1150 of which 40% are successes.
Wednesday, November 7, 2012 at 6:27pm by Eva

algebra
55% of the people in a town have brown eyes. you choose a random sample of 200 people to survey regarding their eye color. What is the mean and standard deviation of the proportion of people in your sample that have brown eyes?
Sunday, January 16, 2011 at 8:07pm by Anonymous

Math Help Please? c: Thank you :3
At your summer job with a research company, you must get a random sample of people from your town to answer a question about spending habits. Which of the following methods is most likely to be random? A) You survey customers at the local shopping mall. B) You survey people ...
Thursday, April 10, 2014 at 4:44pm by X3 ISayRawr

math
a random sample of 42 college graduates who worked during their program revealed that a student spent an averge of 5.5 yeas on the job before being promoted. The sample standard deviation was 1.1 yrs. Using the .99 degree of confidence, what is the confidence interval for the ...
Tuesday, October 25, 2011 at 10:46pm by Dalila

statistics
Suppose that large dogs weights are normally distributed with a mean of 100 pounds and a standard deviation of 10 pounds. If one of these dogs is picked random: a) what is the probability that the dog will weigh over 110 pounds? b) what is the probability that the dog will ...
Friday, March 26, 2010 at 9:30pm by Anonymous

Statistics
#1- The normal distribution had a mean of 14 and standard deviation of 4. There were 30 people in the study group and the average was expected to be 16. The study was tested at the .05 level of significance. What was the power of the study? 74.2% 80.5% 86.4% 92.7% #2- If a ...
Friday, May 14, 2010 at 2:33pm by David

statistics
Starting with a population that is normally distributed with a mean of 100 and a standard deviation of 12, answer the following questions (if possible). a. What is the probability of randomly drawing a single score between 100 and 106, p(100 < X < 106)? b. What is the ...
Saturday, October 15, 2011 at 4:04pm by Daniel

math
identify the variable, population and is this quantitative or qualitative The archaeological site of Tara is more than 4000 years old. Tradition states that Tara was the seat of the high kings of Ireland. Because of it's archaeological importance, Tara has received extensive ...
Saturday, June 8, 2013 at 1:43pm by marie

statistics
Statistical Abstracts (117th edition) provides information aboutthe number of registered automobiles, including taxis, by state. The number ofregistered automobiles per 1,000 residents follows an approximately normaldistribution with mean = 514.6 and standard deviation = ...
Thursday, April 19, 2012 at 11:14am by Anonymous

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 ...
Saturday, June 25, 2011 at 9:15pm by vina

Statistics
1. Suppose the distribution of birth weights of babies born at Big General Hospital is normal. If the mean weight is 7.5 lb. and the standard deviation is 1.25 lb, about 50% of the babies will weight between.... 2. Joe runs a carnival game in which he charges $2 for a player ...
Thursday, April 26, 2012 at 8:32pm by Linda

Statistics
(A) I don't know if your "x" stands for an individual score or the sample mean. If individual score, ignore sample size. Z = (score-mean)/SD If sample mean: Z = (score-mean)/SEm SEm = SD/√n (A) We still don't have your Table 3 or know what it is.
Tuesday, October 25, 2011 at 7:52am by PsyDAG

statistics
A random sample of n=36 scores is selected from a population. Will this have a definite normal distribution?
Thursday, March 17, 2011 at 10:33am by Leticia

math
They are a random sample of people or possibly wine drinkers, so their results can be generalized to whichever population.
Wednesday, April 3, 2013 at 4:23pm by PsyDAG

Prob and Stat
Use a one-sample z-test. Formula: z = (sample mean - population mean)/(standard deviation divided by the square root of the sample size) With the data in your problem: z = (58000 - 60000)/(7000/√49) Finish the calculation. If the test statistic exceeds the critical value...
Tuesday, May 17, 2011 at 2:15pm by MathGuru

statistics
List below are the duration (in hours) of a simple random sample of all flights of a space shuttle program. Find the range, variance, and standard deviation for the sample data. Is the lowest duration time unusual? Why or hwy not? 73 95 238 199 166 268 198 374 260 235 382 339 ...
Tuesday, October 29, 2013 at 6:46pm by angela

Probability and Statistics
A research psychologist believes that professional athletes tend to be more confident than the typical person. From previous testing, he knows that the scores for people in the general population are approximately normally distributed with a mean of 72 and standard deviation ...
Sunday, April 29, 2012 at 7:52pm by Kim

MATH-STAT
You can use a one-sample z-test. z = (sample mean - population mean)/(standard deviation divided by the square root of the sample size) With your data: z = (81.5 - 84)/(10/√75) = ? I'll let you finish the calculation. If you use a 1% significant level for a two-tailed ...
Thursday, November 21, 2013 at 2:53pm by MathGuru

math
1) sounds fine. 2) How can you determine the percentages without knowing the Standard Deviation? You need a measure of variability. 3) The probability of picking a reduced DC is 1/6, not reduced = 5/6. The probability of picking 2 of each is 1/6 * 1/6 * 5/6 * 5/6 (multiply). 4...
Saturday, February 9, 2008 at 1:39pm by PsyDAG

statistic
Suppose a random sample of 25 students is selected from a community college where the scores in the final exam (out of 125 points) are normally distributed, with mean equal to 112 and standard deviation equal to 12. Find the probability that the sample mean deviates from the ...
Thursday, November 8, 2012 at 12:40am by Coco

statistics
Among 17 metal parts produced in a machine shop, 6 are defective. If a random sample of four of these metal parts is selected, find: (a) The probability that this sample will contain at least three defectives. (Do not round the intermediate answers. Round your answer to 4 ...
Friday, April 8, 2011 at 2:36pm by Kate

Statistics
The null and alternate hypotheses are: H0: μ1 = μ2 H1: μ1 ≠ μ2 A random sample of 15 items from the first population showed a mean of 50 and a standard deviation of 5. A sample of 12 items for the second population showed a mean of 46 and a standard ...
Sunday, October 21, 2012 at 8:28pm by Anonymous

Math
The IQ scores are normally distributed with a mean of 100 and a SD of 15. A) What is the probability that a randomly person has an IQ b/t 85-115? Show work B) Find the 90th percentile of the IQ distribution? C) If a random sample of 100 people are selected, what is the SD of ...
Friday, March 8, 2013 at 11:27am by Sandy

Statistics
Take the standard deviation and divide it by the square root of the sample size.
Monday, November 15, 2010 at 5:28pm by MathGuru

statistics
Take standard deviation and divide it by the square root of the sample size.
Thursday, May 12, 2011 at 7:20pm by MathGuru

Statistics
Find t-value for sample size n = 16 and area to the right 0.10
Wednesday, February 22, 2012 at 6:31pm by Tina

Stats
Take standard deviation and divide by the square root of the sample size.
Thursday, August 23, 2012 at 4:32pm by MathGuru

stats
Use n1 + n2 - 2 for degrees of freedom. Note: n = sample size
Tuesday, March 5, 2013 at 12:11pm by MathGuru

Statistics
mean = np n = sample size = 64 p = .25 I'll let you take it from here.
Sunday, June 2, 2013 at 11:24pm by MathGuru

statistics
The larger the sample size, the more you can safely approximate the normal distribution.
Monday, November 18, 2013 at 11:00pm by MathGuru

statistics
You are a travel agent and wish to estimate, with 98% confidence, the proportion of vacationers who use an online service or the Internet to make travel reservations. Your estimate must be accurate within 4% of the population proportion. a) No preliminary estimate is available...
Wednesday, April 6, 2011 at 4:12pm by alex

Statisics
I need help on this question i am confused. I don't think the answers i got are right The library checks out an average of 320 books per day, with a standard deviation of 75 books. Suppose a simple random sample of 30 days is selected for observation. What is the probability ...
Sunday, February 20, 2011 at 7:04pm by Mike

statistics
you are asked to estimate the average weight of an adult male passenger for a study to maximize the number of seats in a certain airplane. you collect random weights of 1000 men passengers from a population of 100,000. you find that the average man in the sample weighs 180 ...
Monday, December 19, 2011 at 12:40pm by KK

Statistics
Consider the hypothesis test given by Ho:u=530, H1:u does not equal 530. In a random sample of 85 subjects, the sample mean is found to be 522.3. Also, the population standard deviation is 29. Determine the P-value for this test. Is there sufficient evidence to justify the ...
Friday, March 8, 2013 at 9:35pm by Sandy

statistics
2) Two individuals are running for mayor of Tallahassee. You conduct an election survey (N = 561) a week before the election and find that 57% of the respondents prefer candidate A. Can you predict the winner (α = 0.01)? (Hint: Use 50% as the proportion of votes needed ...
Wednesday, March 18, 2009 at 10:12pm by taryn

statistics
the weights of shells follow a normal distribution. a random sample of 12 hybrid shells a a mean weight of 1.7 pounds with standard deviation 0.24 pounds. Find a 95 % confidence interval level for the mean weight if the fall catch is within 0.1 pounds of the sample estimate
Thursday, March 21, 2013 at 12:47am by Lost37

statistics
Find the definitions of systematic, cluster, and random sampling. One hint: for random sampling, a random number table can be used to choose samples.
Monday, November 14, 2011 at 5:24pm by MathGuru

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 ...
Thursday, December 29, 2011 at 2:48pm by rich

Statistics
Identify whether the variable in the information below is qualitative or quantitative. The archeological site of Tara is more than 4000 years old. Tradition states that Tara was the seat of the high kings of Ireland. Because of its archeological importance, Tara has received ...
Thursday, June 24, 2010 at 3:37pm by vane

Statistics
Identify whether the variable in the information below is qualitative or quantitative. The archeological site of Tara is more than 4000 years old. Tradition states that Tara was the seat of the high kings of Ireland. Because of its archeological importance, Tara has received ...
Thursday, June 24, 2010 at 3:37pm by vane

social psy
I want to utilize a true experimental design to study the effects of classical music exposure on the cognitive development of newborns. a- What is an independent variable? b- What is a dependent variable? c-What is random assignment? d-Why is random assignment important? e-...
Monday, October 3, 2011 at 2:24pm by deb

heathCare
EXAMPLE 3 Telephone Book Sampling You want to conduct an opinion poll in which the population is all the residents in a town. Could you choose a simple random sample by randomly selecting names from the local telephone book? Solution A sample drawn from a telephone book is not...
Wednesday, November 12, 2008 at 11:14pm by Danny

statistics/ Help!-thanks!
I would phrase the hypotheses this way: Ho: ≥ 1.73 Ha: < 1.73 This would be a one-tailed test since Ha is showing a specific direction (less than). Use a z-test: z = (sample mean - population mean)/(standard deviation divided by the square root of the sample size...
Saturday, August 25, 2012 at 4:28pm by MathGuru

health help me......
This is not scientific, but I've noticed that smaller beings (babies, cats, dogs, etc.) breathe faster than adult humans do. It has to do with size -- size of body, size of lungs ...
Wednesday, November 5, 2008 at 8:57pm by Writeacher

Statistics
There is a random selection of 150 students. What is the probablity that the sample percentage of correct identification is greater than 75%?
Tuesday, June 18, 2013 at 11:38pm by Katie

statistics
a recent study by a large retailer designed to determine whether there was a relationship between the importance a store manager placed on advertising and the size of the store revealed the following sample information: observed frequencies(sample)small-medium-large what kind ...
Thursday, February 23, 2012 at 10:30pm by markeda

statistics
THIS WAS MY ANSWER a)Identify the population and the sample. N (population) is ALL phones produced per day n (sample) is 40 random phones from the days production b) Is the population parameter in this study known or unknown? Explain. UNKNOWN - Parameter is the numerical ...
Wednesday, February 22, 2012 at 3:10pm by Alyssa

alegbra
Which of the following are examples of inferential statistics? Check all that apply. A.Finding the average (mean) of a set of numbers B.Testing every lightbulb produced by a company to confirm that each one works C.Testing random samples of lightbulbs produced by a company to ...
Tuesday, April 17, 2012 at 8:07pm by daryl

statistics
Find the minimum sample size that should be chosen to assure that the proportion estimate p will be within the required margin of error, .06. Use a 95% confidence interval and a population proportion of .7. The critical value for a 95% confidence level is 1.96 Find the test ...
Sunday, October 14, 2012 at 6:04pm by Ari

STATISTICS
The number of boxes of girl scout cookies sold by each of the girl scout in a city has a distribution which is approximately normal with a mean=75 boxes and a standard deviation=30 boxes.... 1.) find the probability that scout chosen at random sold between 60 and 90 boxes. 2...
Wednesday, August 10, 2011 at 12:50pm by Mason

statistics
A random sample of 84 shoppers were interviewed and 51 said they prefer to shop alone rather than with someone such as friends or family. Let p represent the proportion of all shoppers at this mall who would prefer to shop alone. Find a point estimate for p from the sample ...
Friday, August 17, 2012 at 5:26pm by Anonymous

business statistics
If a sample of size 30 is selected, the value of A for the probability p(>- A) = 0.01 is?
Saturday, August 1, 2009 at 11:07am by Bryant

statistics
If a sample of size 30 is selected, the value of A for the probability P(t greater or less A) = 0.01 is?
Saturday, August 1, 2009 at 8:20pm by Lina

Statistics
Formula used to easily calcuate sample size. Please give example.
Tuesday, January 26, 2010 at 10:05am by Bryant

statistics
CI90 = p + or - 1.645 [√(pq/n)] ...where p = .40, q = 1 - p, n = sample size. I'll let you take it from here.
Monday, November 8, 2010 at 9:38pm by MathGuru

science
1) mass and volume 2) No. The density would be the same for that material no matter what the sample size is
Tuesday, March 29, 2011 at 10:09pm by drwls

Statistics
degree of freedom for a chi-test depends on the sample size true or false
Sunday, May 15, 2011 at 4:06pm by Anonymous

biostatistic
False. For smaller effect sizes a larger sample size would be required.
Tuesday, December 11, 2012 at 1:06pm by MathGuru

7th grade Math
If there is a population of 800 deer what would be a good sample size and why.
Friday, September 6, 2013 at 3:24am by Brandi

math-stupid stat
You can use a one-sample z-test. z = (sample mean - population mean)/(standard deviation divided by the square root of the sample size) With your data: z = (11.6 - 13)/(1.3/√7) = ? Finish the calculation. If you use an alpha of .02 for a two-tailed test, then the cutoff ...
Thursday, November 21, 2013 at 2:56pm by MathGuru

STATISTICS PLEASE HELP!!!!!
are you a chocolate "purist", or do you like other ingredients in your chocolate? american demographics reports that almost 75% of consumers like traditional ingredients such as nuts or caramel in their chocolate. they are less enthusiastic about the taste of mint or coffee ...
Wednesday, November 3, 2010 at 11:11pm by Brittany

John jay college
Sample mean from a sample of size n from a normal population with mean μ and σ has parameters N(μ,σ²/n) Since n=9, σ=9, σ²/n=9, so the sample mean ~ N(50, 3²). Z-score=((M-μ)/σ)=(59-50)/3=3
Sunday, July 22, 2012 at 5:59pm by MathMate

business
MGT635-1003B-04 International Business Operations Management Assignment Name: Unit 5 Individual Project Deliverable Length: 6-7 body pages Details: As the production manager for an electronic circuit company you have encountered the following situation. Part 1 A process for ...
Sunday, August 15, 2010 at 11:08pm by 1SGCalhoun

algebra 1
From a shipment of 350 light-bulbs, a sample of 70 was selected at random and tested. If 21 light-bulbs in the sample were found to be defective, how many defective light-bulbs would be expected in the entire shipment?
Sunday, September 18, 2011 at 5:22pm by alex

statistics
The ages of commercial aircraft are normally distributed with a mean of 13.0 years and a standard deviation of 7.5 years what percentage of individual aircraft have ages greater than 15 years assume that a random sample of 49 aircraft is selected and the mean age of the sample...
Tuesday, April 24, 2012 at 8:26pm by Tanya

chemistry
consider a random mixture of two particles,diamond and SiC.Assume all particles are spherical with a radius of 0.100mm. The mixture is 80.0 wt% diamond(density=3.51 g/ml) and 20.0 wt% SiC (density=3.23 g/ml) a)Calculate the mass of a single particle diamond and the number of ...
Tuesday, October 2, 2012 at 12:02pm by mahtab

statistics
Suppose a random sample of 25 students is selected from a community college where the scores in the final exam (out of 125 points) are normally distributed, with mean equal to 112 and standard deviation equal to 12. Find the probability that the sample mean deviates from the ...
Monday, October 31, 2011 at 5:33pm by Monique

statistics
A film alliance used a random sample of 50 U.S. citizens to estimate that the typical American spent 78 hours watching videos and DVDs last year. The standard deviation of this sample was 9 hours. (a) Develop a 95 percent confidence interval for the population mean number of ...
Wednesday, April 24, 2013 at 8:02pm by Anonymous

Math
What is the propability that a random sample of 30 days in august has a mean high tempature less then 78 degreese?
Saturday, October 30, 2010 at 4:19pm by Sherrie

statistics
Let X be the average of a sample of 16 independent normal random variables with mean 0 and variance 1. Determine c such that P (X< c) = .5
Wednesday, March 9, 2011 at 12:07am by Anonymous

Research Methods
well.. 35 students showed up.. but fifteen were only chosen.. which would then be a random sample? right..?
Saturday, October 15, 2011 at 6:01pm by Jill

statistic
in a random sample of 400 voter, 120 plan to vote for candidate A. determine a 95% confidence interval
Thursday, November 1, 2012 at 12:46am by John

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