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November 26, 2014

# Search: A random sample of size n is to...

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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?
November 15, 2010 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?
November 9, 2011 by Janelle

statistics
The average temperature in households is 67.6 degrees F. The standard deviation is 4.2 degrees F. A random sample of 51 households is to be selected What is the probability that the average of this sample will be within 1.4 STANDARD ERRORS of the population mean?
September 28, 2012 by Kristin

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 ...
February 14, 2013 by Aboli

ap stats need help
Continuous Random Variable, I Let X be a random number between 0 and 1 produced by the idealized uniform random number generator described. Find the following probabilities: a.P(0ˇÜXˇÜ0.4) b.P(0.4ˇÜXˇÜ1) c.P(0.3ˇÜX0.5) d.P(0.3(<X<0.5) e.P(0.226ˇÜXˇÜ0.713) f.What ...
March 10, 2009 by chris

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 ...
April 29, 2012 by Kim

statistics
A random sample of 384 people in Dalto City, a mid-sized city, revealed 112 individuals who work at more than one job. A second random sample of 432 workers from East Dettweiler, another mid-sized city, found 91 people who work at more than one job. To conduct a significance ...
October 26, 2012 by Derp

statistics
A random sample of 384 people in Dalto City, a mid-sized city, revealed 112 individuals who work at more than one job. A second random sample of 432 workers from East Dettweiler, another mid-sized city, found 91 people who work at more than one job. To conduct a significance ...
November 4, 2012 by John

Statistics
A random sample of 384 people in Dalto City, a mid-sized city, revealed 112 individuals who work at more than one job. A second random sample of 432 workers from East Dettweiler, another mid-sized city, found 91 people who work at more than one job. To conduct a significance ...
November 5, 2012 by John

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

Statistics
A large furniture store has begun a new ad campaign on local television. Before the campaign, the long term average daily sales were \$24,819. A random sample of 40 days during the new ad campaign gave a sample mean daily sale of x(bar)=\$25,910 with sample standard deviation s...
May 9, 2012 by Matt

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 ...
August 15, 2010 by 1SGCalhoun

statistics
A simple random sample of 40 items resulted in a sample mean of 25. The population standard deviation is 5. a. What is the standard error of the mean (to 2 decimals)? b. At 95% confidence, what is the margin of error (to 2 decimals)?
April 21, 2014 by Vanessa

Data Structures and Algorithms
The "random" numbers produced by computers aren't purely random. They are actually pseudo-random, meaning that they are produced by mathematical formulas that simulate randomness.The linear congruential generator takes a seed X0 and generates subsequent pseudo-random numbers ...
July 22, 2013 by John Berkhamp

Statistics
How long does it take to have food delivered? A Chinese restaurant advertises that the mean delivery will be no more than 30` minutes. A random sample of delivery times is shown below. Based on this sample data, is the mean delivery time different than 30 minutes? Use a 5% ...
March 25, 2012 by Jasmine

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 ...
November 11, 2009 by sandy

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 ...
October 27, 2013 by Shelby

Sampling A manufacturing company's quality control personnel have recorded the proportion of defective items for each of 500 monthly shipments of one of the computer components that the company produces. See data below. The company doesn't have time to review all of these. (a...
March 20, 2011 by Carolina

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 ...
October 21, 2012 by Anonymous

statistics
the assets (in billions of dollars)of the four wealthiest people in a particular country are 46,34,12,10. Assume that the samples of size 2 are randomly selected with replacement from this population of four values. After listing the possible sample and finding the mean of ...
December 20, 2011 by nannie

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 ...
February 23, 2012 by markeda

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

Statistics
The effect size in this hypothetical trial (2.7 fewer infections per 1000 vaccinated) is slightly smaller than the effect size found in the real 2009 HIV vaccine trial (2.8 fewer infections per 1000 vaccinated); so why is the p-value smaller? The hypothetical trial has less ...
July 15, 2013 by Rupal

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 ...
October 29, 2013 by angela

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

statistics
A random sample of 100 of a population Mean is 31 and standard deviation 22 Approximate probability of 28
April 27, 2013 by Dorri

Statistics
Formula used to easily calcuate sample size. Please give example.
January 26, 2010 by Bryant

statistics
Sample size is 24, Mean rate of 6.50%, Standard Deviation is 1.20. Calculate 90% of confidence interval
October 14, 2010 by sue

chemistry
what sample size of .9181M vinegar would require 27.50 mL of .5185M of NaOH for neutralization?

Math
Determine whether a correlation coefficient of r = –0.405 is significant at the 5% level for a sample size of 22
January 27, 2012 by Constance

If there is a population of 800 deer what would be a good sample size and why.
September 6, 2013 by Brandi

Math
Determine whether a correlation coefficient of r = 0.471 is significant at the 5% level for a sample size of 20.
July 12, 2014 by Shelagh

statistics
Twelve different video games showing substance use were observed and the duration times of game play (in seconds) are listed below. The design of the study justifies the assumption that the sample can be treated as a simple random sample. Use the sample data to construct and ...
July 7, 2014 by Teniqua Evans

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 ...
April 10, 2014 by X3 ISayRawr

STAT
1. In a study of the income of U.S. factory workers, a random sample of 100 workers shows a sample mean of \$35,000. Assume that the population standard deviation is \$4,500, and that the population is normally distributed. A) Compute the 90%, 95% and 99% confidence intervals ...
November 2, 2014 by Hugh

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 ...
November 8, 2012 by Coco

Statistics
(TCO A) Consider the following age data, which is the result of selecting a random sample of 20 United Airlines pilots. 47 45 45 52 58 55 58 44 42 38 45 52 48 47 51 45 52 42 37 40 a. Compute the mean, median, mode, and standard deviation, Q1, Q3, Min, Max for the above sample ...
September 6, 2012 by Pat

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 ...
December 19, 2011 by KK

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?
January 16, 2011 by Anonymous

Statistics
please help having difficulty with this problem. It was noted that 40% of the people in Dallas read the morning newspaper. A random sample of 18 people is selected from the city. On average, how many people would you expect to read the morning newspaper in a sample of 18?
December 13, 2012 by Stacy

Statistics
A quality control inspector wants to estimate the mean inside diameter of the washers produced by a certain machine. A preliminary sample indicates that the inside diameters have a standard deviation of 0.30 millimeters. What sample size does he need to estimate the mean to ...
December 6, 2012 by Carolyn

Statistics
From random sample of 200 college students, 40 students indicated that they smoke cigarettes. Use the information from the sample to calculate a 95% confidence interval for the population proportion of college students that smoke cigarettes (round to nearest hundredth). A. (0....
May 18, 2012 by Mary

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 ě = 514.6 and standard deviation ó = ...
April 19, 2012 by Anonymous

Statistics
Calculate the following: a) Determine the sample size necessary to estimate a population mean to within 1 with a 90% confidence given that the population standard deviation is 10. b) Suppose that the sample was calculated at 150. Estimate the population mean with 90% confidence.
March 13, 2010 by Tom

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?
April 25, 2010 by Lilly

statistics
According to the MIT Airline Data Project, American Airlines controlled 15.5% of the domestic market in 2010. A random sample of 125 domestic passengers that year was selected. Using the normal approximation to the binomial distribution, what is the probability that more than ...
July 20, 2014 by james

Statistics
Total plasma volume is important in determining the required plasma component in blood replacement theory for a person undergoing surgery. Plasma volume is influenced by the overall health and physical activity of an individual. Suppose that sample of some male firefighters ...
July 7, 2012 by Desperate

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
March 21, 2013 by Lost37

Econ 112
A researcher believes that the average size of farms in the U.S. has increased from the 2002 mean of 471 acres. She took a sample of 23 farms in 2011 to test her belief and found a sample mean of 498.8 acres and a sample standard deviation of 46.9 acres. At a 5% levelof ...
June 18, 2013 by Help

Math
What is the propability that a random sample of 30 days in august has a mean high tempature less then 78 degreese?
October 30, 2010 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
March 9, 2011 by Anonymous

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

Algebra 2: Prob and Stats
Find the sample size that produces the margin of error +-4.0% a) 325 b) 25 c) 16 d) 625
May 24, 2010 by Skye

statistical applicatons
Why is it important to learn what sample size was used in a study in which no statistica difference was found?
July 10, 2010 by Jerry

statistics
What is the relationship between Sample Size and the width of the Confidence Interval? Please explain further as to why
September 16, 2011 by denise

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...
April 24, 2012 by Tanya

Math
James Profit wants to take National Widget Company public. He is interested in the relationship between the size of the initial public offering and the price per share. A sample of 10 companies that recently went public revealed the following information: size(\$M)price per ...
September 15, 2008 by Student

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 ...
November 3, 2010 by Brittany

Statistics
An investigational drug study is being conducted. The initial screening phase needs to include enough people so that the final (approved) group has at least 10 patients. The probability of a person being approved for the study is .80. what initial sample size is needed to make...
June 6, 2009 by Craig

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 ...
April 8, 2011 by Kate

Algebra 2
Suppose you did a survey of male shoes size and the mean of that survey was size 10 with a standard deviation of 1.5. What is the z-score of a size of 7.5?

Math
Suppose you did a survey of male shoes size and the mean of that survey was size 10 with a standard deviation of 1.5. What is the z-score of a size of 7.5?
June 7, 2011 by Wyeth

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-...
October 3, 2011 by deb

math statistics
The average price of a gallon of unleaded regular gasoline was reported to be \$2.34 in northern Kentucky (The Cincinnati Enquirer, January 21, 2006). Use this price as the population mean, and assume the population standard deviation is \$.20. 1. What is the probability that ...
October 19, 2009 by aaron

math statistics
please help me I've waited for hours The average price of a gallon of unleaded regular gasoline was reported to be \$2.34 in northern Kentucky (The Cincinnati Enquirer, January 21, 2006). Use this price as the population mean, and assume the population standard deviation is \$....
October 19, 2009 by aaron need urgent help

Statistics
Maureen is a cocktail hostess in a very exclusive private club. The IRS is auditing her tax return. Maureen claims that her average tip last year was \$4.75. To support this claim, she sent the IRS a random sample of 52 credit card receipts showing her bar tips. When the IRS ...
May 5, 2013 by Kay

statistics
a random sample of 80 college students was selected to participate in a experiment. the mean of the sample is 317 points, the standard deviation of 37 there are 310 students that didn't complete the experiment 1. compute the appropriate test statistic? 2. what is the critical ...
July 11, 2012 by Anonymous

statistics
In this unit we have worked with scores and their locations within a distribution. This discussion is designed to get you to think a little more about distributions of scores. Shown below are two samples of scores. Input these scores into SPSS and use plots and data ...
February 26, 2012 by john

Math
In a random sample of 30 tires of the same type, it is found that the average life span is 36,200 miles with a standard deviation of 3800 miles. Find the interval about the sample mean such that the probability is 0.77 that the mean number lies within the interval. a. 35,402-...
July 3, 2009 by Sophie

Statistics
When finding a confidence interval for a population mean based on a sample of size 11, which assumption is made? The standard deviation is fixed. The sampling distribution of z is normal. The sampling distribution of the sample means is approximately normal. There is no ...
October 26, 2012 by What?

STATISTICS
1. What if the size for each sample were increased to 20? Would a sample mean of 115 or more be considered unusual? Why or why not? 2. Why is the Central Limit Theorem used? 3. Consider situations in your work or home that could be addressed through a continuous probability ...
February 2, 2012 by B

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 ...
October 31, 2011 by Monique

Statistics
In a population, heights of males are normally distributed with u=180 cm and sigma^2=16 cm^2, while the heights of females are normally distributed with u=170 cm and sigma^2= 25 cm^2. a) One random male and one random female are selected from the population i)What is the ...
November 9, 2014 by William

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 ...
April 17, 2012 by daryl

Statistics
A random sample of 50 students has a test score average with a standard deviation of 10.9. Find the margin of error if c = 0.90.
November 28, 2009 by Jessica

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

geometry
A number is selected at random from the set {2, 3, 4, … 10}. Which event, by definition, covers the entire sample space of this experiment?
July 24, 2014 by cfd

statistics
there are 450 employee in an organization. using the method of random sampling numbers, select a sample of 20 employees
September 8, 2014 by Anonymous

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 ...
August 17, 2012 by Anonymous

statistics
There are 120 possible samples of size n=3 which can be drawn from this population of 10 scores: 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 Write each sample and calculate its mean
June 15, 2010 by Joe

statistics
how large a sample size is needed for 2 sided 95% confidence interval to have a length of 2 weeks when mean is 3.6
June 28, 2012 by jo

stats
if i have a sample size of 200, 16% are poor, what is my mean and standard deviation. my answers do not make any sense
January 1, 2013 by gary

Statistics
Find the critical values x2L and x2R that correspond to the given confidence level and sample size. 99%: n=23
June 30, 2014 by Kasey

statistics
An important indicator of lung function is forced expiratory volume(FEV), which is the volume of air that a person can expire in one second. Dr. Jones plans to measure FEv in a random sample of n young women from a certain population, and to use the sample mean as an estimate ...
February 16, 2008 by lauren

statistics
1. A state’s department of education reports that 12% of the high school students in that state attend private schools. The state university wonders if the percentage is the same in their applicant pool. Admissions officers plan to check a random sample of the over 10,000 ...
November 17, 2011 by fast eddie

statistics
The following table shows the summary statistic of the cholesterol levels of two groups of men in 2014. From 25 to 40 years old, the mean is 224, standard deviation is 5.5 and the sample size is 12. From 41 to 55 years old, the mean is 230, standard deviation is 7 and the ...
November 15, 2014 by poon

AP tatistics
A horticulturist wishes to estimate the mean growth of seedlings in a large timber plot last year. A random sample of n = 100 seedlings is selected and the one-year growth for each is measured. The sample yields = 5.62 cm. The known standard deviation for this popualtiopn is ...
April 21, 2013 by Ann

statistics
a random sample of 100 college students is taken from the student body of a large university. assume that a population mean of 20 hours and a population standard deviation of 15 hours describes the weekly study estimates for the entire student body. About 68 percent of the ...
June 27, 2010 by jc

statistics
At a large publishing company, the mean age of proofreaders is 36.2 years, and the standard deviation is 3.7 years. If a random sample of 15 proofreaders is selected, find the probability that the mean age of the proofreaders in the sample will be between 36 and 37.5 years....
October 22, 2010 by Cindy

Spanish
Need help with this activity: Imagine that in your backpack you have several writing implements, all of which are the same size: 2 lápices, 5 bolígrafros, 3 marcadores. If you pull one out at random, what is the percent probability that it will be a marker? a. 20% b. 50% c. 30...
November 14, 2010 by mysterychicken

Spanish
Need help with this activity: Imagine that in your backpack you have several writing implements, all of which are the same size: 2 lápices, 5 bolígrafros, 3 marcadores. If you pull one out at random, what is the percent probability that it will be a marker? a. 20% b. 50% c. 30...
November 15, 2010 by mysterychicken

marketing
Binomial probability distributions are used in business, science, engineering, and other fields. Suppose you work for a marketing agency and have to create a television ad for Brand A toothpaste. The toothpaste manufacturer claims that 40% of the toothpaste buyers prefer Brand...
September 27, 2012 by Mark

Statistics
A national opinion poll found that 44% of all American adults agree that parents should be given vouchers good for education at any public or private school of their choice. Suppose that in fact the population proportion who feel this way is p=0.44. A) Many opinion polls have ...
December 17, 2013 by JJ

statistics
One of the ways most people relieve stress is to reward themselves with sweets. According to one study in Food Technology, 46 percent admit to overeating sweet foods when stressed. Suppose that the 46 percent figure is correct and that a random sample of 100 people is selected...
July 1, 2014 by Alfie

Stats 330- HELP
I need some help on this question it has two parts but i can't figure it out. Can someone help me. The NDSU 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...
March 10, 2011 by John

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 ...
April 24, 2013 by Anonymous

statistics
Annual household incomes in a certain region have a distribution that is skewed right, with mean 30.25 thousand dollars and a standard deviation of 4.50 thousand dollars. If a random sample of 100 households is taken, then the probability that the sample mean Ż x will be ...
August 9, 2010 by houston

statistics
Workers in several industries were surveyed to determine the proportion of workers who feel their industry is understaffed. In the government sector, 37% of the respondents said they were understaffed, in the health care sector 33% said they were understaffed, and in the ...
October 20, 2014 by tia

Statistics
A company has developed a new type of light bulb, and wants to estimate its mean lifetime. A simple random sample of 12 bulbs had a sample mean lifetime of 692 hours with a sample standard deviation of 30 hours. It is reasonable to believe that the population is approximately ...
July 1, 2013 by Sara

Probability and Statistics
The major would like to estimate the mean number of automobile crashes per day at the intersection of 2 highways. A random sample of 40 days worth of data had a mean of 4.3 crashes and a standard deviation of 0.9. How large of a sample would be needed in order to produce a 95...
April 29, 2012 by Kim

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