Wednesday
December 7, 2016

Search: Standard Deviation

Number of results: 9,893

Statistic
A random sample of size 20 drawn from a normal distribution has a sample mean of 8 and a sample standard deviation of 4. A) Compute the sample test statistic t under the null hypothesis H_0: Mue(mean)=7 B) State the alternate hypothesis if you believe that the population mean ...
December 4, 2014 by Yira f

statistics
The physical plant at the main campus of a large state university receives daily requests to replace florecent lightbulbs. The distribution of the number of daily requests is bell-shaped and has a mean of 37 and a standard deviation of 3. Using the empirical rule (as presented...
October 31, 2014 by Huong Nguyen

stats
Scores on a test are approximately normally distributed with a mean of 70 and a standard deviation of 9. The teacher wants to give A’s to the top 10% of students, B’s to the next 25%, and C’s to the next 42%. a.) what is the bottom cutoff for a C grade? b.) what is the ...
April 25, 2016 by vanessa

Bio
im stuck on these questions for my study guide Please help! i don't want links. thanks 1. Which of the follwoing would be an appropriate measure of the phenotypic variation of a trait in a population? a) the mean of the trait in the population b) the standard deviation of the ...
May 25, 2011 by Philip

statistics
Assume the population distribution of FEV is normal with standard deviation 400 mLi. (a) find P(E) is n=15 and population mean is 2800 mLi (B) find P(E) is n=15 and the population mean is 2600mLi (C) How does P(E) depend on the population mean?
October 13, 2009 by Sam

statistics
Among coffee drinkers, men drink a mean of 2.8 cups per day with a standard deviation of 0.5 cups. Assume the number of drinking per day follows a normal distribution. What proportion drink 3 cups per day or more?
February 20, 2012 by Bri

statitics
Certain data includes 36 body temperatures for which the sample mean is equal to 98.20 °F and standard deviation of 0.62 °F. Using this sample statistics, construct a 95% confidence interval of the mean body temperature. What does the sample suggest about the use of 98.6°F ...
May 19, 2014 by statitics

math
No idea how to do this. I looked in my book and there usually is a data set present to get the first, second and third quartile. The lifetimes of lightbulbs of a particular type are normally distributed with a mean of 392 hours and a standard deviation of 9 hours. Find the ...
April 22, 2007 by J

homework statistics
Consider a random sample with sample mean x. If the sample size increased from n = 40 to n = 360, then the standard deviation of x will: a. remain the same b. increase by a factor of 9 (will be multiplied by 9) c. decrease by a factor of 9 (will be multiplied by 1/9) d. ...
July 22, 2011 by Jackay 70

statistics
Someone who has never seen a normal die before decides to estimate the mean value of all its faces (μ) by rolling it many times. First, they are told that the standard deviation is σ = 1.7. Then, they roll the die 50 times and get a sample mean of x-bar = 3.7. ...
January 29, 2012 by Nadia

computers
Although label choices vary for different printers, your textbook recommends __________ for laser and ink jet printers. A. Avery standard, 5160, Address B. Avery standard, 6150, Label C. Avery standard, 6150, Address D. Avery standard, 5160, Label I've looked through the book...
June 27, 2012 by julia

statistics probability
Alice earned a score of 940 on an IQ test.The mean test score was 850 with a standard deviation of 100.(Assume that test scores are normally distributed). Q1a).What proportion of students had a higher score than alice? Qb)Find the score exceeded by 2.5% of the students.
November 14, 2010 by koo

Stats
Consider the following Hypotheses test: Ho:m>=80 Ha:m<80 A sample of 121 provided a sample mean of 77.3. The population Standard Deviation is known to be 16.5. A. compute the value of test statistic B. Determin the p value: and at 93.7% confidence, Test the above ...
April 29, 2012 by bobbie

statistics
A vending machine is designed to dispense a mean of 7.6 oz of coffee into an 8-oz cup. If the standard deviation of the amount of coffee dispensed is 0.4 oz and the amount is normally distributed, find the percent of times the machine will a) dispense less than 7.0 oz. b) ...
November 20, 2012 by vinnie

Statistics
A random sample of 50 students chosen from an elementary school with 400 students was found to have a mean allowance of $26 per week with a standard deviation of $8. Obtain a 98% confidence interval for the total amount of allowance money given to students in this school per ...
November 13, 2013 by Cam

Statistics
The distribution of a sample of the outside diameters of PVC gas pipes approximates a symmetrical, bell-shaped distribution. The arithmetic mean is 11.0 inches, and the standard deviation is 2.0 inches. About 68 percent of the outside diameters lie between what two amounts? 8....
March 27, 2014 by Shawn

Algebra 2
A simple random sample of 50 adults was surveyed, and it was found that the mean amount of time that they spend surfing the Internet per day is 54.2 minutes, with a standard deviation of 14.0 minutes. What is the 99% confidence interval for the number of minutes that an adult ...
December 9, 2014 by Jasmine

statistics
A new national survey found that Americans drink an average of 6 glasses of water daily, instead of the recommended 8. Assuming that the number of glasses of water is approximately normally distributed with a standard deviation of 1.7 glasses, what proportion of Americans ...
April 16, 2015 by MJ

stats
A random sample of 40 men drank an average of 20 cups of coffee per week during examination final, with the population standard deviation equal to 6 cups. A lower limit of an approximate 95% confidence interval the population average cup of coffee is (1) 20.000 (2) 21.859 (3) ...
March 31, 2010 by cindy

Math: i do not understand
A tractor manufacturing company machines axles to extremely small tolerances. The main power axles have a mean diameter of 3.0000 inches and a standard deviation of 0.0050 inch. What is the probability that a given axle will have a diameter between 2.9915 and 3.0004 inches? ...
May 7, 2010 by Bart

ap stats
based on over 800 housing prices collected at random from the city of Los Angeles, an investigator constructed a histogram and found that the distribution of housing prices was heavily skewed to the right. Which of the following statistics will best represent the center of ...
May 13, 2014 by emma

Statistics
Cellular Phone Sales The probability that a cellular phone company kiosk sells X number of new phone contracts per day is shown below. Find the mean, variance, and standard deviation for this probability distribution. X 4 5 6 8 10 P (X) 0.4 0.3 0.1 0.15 0.05 What is the ...
April 10, 2012 by Victor

math PLEASE URGENT
if normal blood cholestrol level is 5.8 mM and a treatment caused a drop of 1.0 mM with a standard deviation of the difference of 2.0 mM what is the minimum number of individuals that should be used in the drug trial to determine whether or not it is effective i know you have ...
June 1, 2010 by lou

Statistics
Thomas economic forecasting, Inc. and Harmon econometrics have the same mean error in forecasting the stock market over the last ten years. However, the standard deviation for Thomas is 30 points and 60 points for harmon.At the .05 signifcance level can we conclude that there ...
August 7, 2010 by Anonymous

statistics
Given that x is a normally distributed random variable with a mean of 60 and a standard deviation of 10, find the P(56 < x <74). Please show all your work and write your answer in a complete sentence. Using the information from question 1, what percentage of the ...
July 23, 2012 by Rachel

statistics
Listed below are the duration's (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 why not? 71 100 237 199 164 269 193 379 252 233 388...
February 11, 2015 by slomo

Finance
Use the following information to calculate the covariance of asset A with an equally weighted portfolio of assets B and C. Asset Standard Deviation A 20% B 30% C 40% The correlation coefficient between A and B is 0.6. The correlation coefficient between A and C is 0.5. The ...
September 22, 2014 by Anonymous

Math-Answer included
{9, 7, 13, 24, 32, 45, 47} First you have to find the mean The mean is 9+7+13+24+32+45+47=177/7=25.2857=25.29 Find the standard deviation for the given data. Round your answer to one more decimal place than the original data. {9, 7, 13, 24, 32, 45, 47} (25.29-9)^2=16.29^2=265....
November 6, 2009 by Anonymous

Math
A consumer buys n light bulbs, each of which has a lifetime that has a mean of 800 hours, a standard deviation of 100 hours, and a normal distribution. A light bulb is replaced by another as soon as it burns out. Assuming independence of the lifetimes, find the smallest n so ...
April 27, 2011 by Alex

Math
A consumer buys n light bulbs, each of which has a lifetime that has a mean of 800 hours, a standard deviation of 100 hours, and a normal distribution. A light bulb is replaced by another as soon as it burns out. Assuming independence of the lifetimes, find the smallest n so ...
April 27, 2011 by Lo

Statistics
Suppose that the average grade for all people who take this course in statistics is 83 with a standard deviation of 3.5. If your particular class has an average of 89, can you conclude that your class is better than average at the 90 percent confidence level? Label and ...
May 13, 2011 by tom

statistics
A state administered standardized reading exam is given to eighth grade students. The scores on this exam for all students statewide have a normal distribution with a mean of 506 and a standard deviation of 69. A local Junior High principal has decided to give an award to any ...
September 4, 2014 by Anonymous

Business Statistics
A filling machine is designed to fill soda bottles with 16 ounces of soda. The distribution for the weight of the bottles is normal. Twenty bottles are selected and weighed. The sample mean is 15.3 ounces and sample standard deviation is 1.5 ounces. Develop a 90% confidence ...
March 16, 2015 by Leo Elvis

P-Chem
The equilibrium constant K for the hydrolysis of adenosine triphosphate (ATP) to adenosine diphosphate (ADP) and phosphate is 1.66X10^5 at 37 degrees celcius, and Standard Delta H is -20.1 kJ/mol. Calculate Standard Delta S for the hydrolysis at 37 degrees celcius. On the ...
October 20, 2006 by Angela

statistics
If we know that the length of time it takes an MBA student to find a parking spot near the DePaul Center follows a normal distribution with a mean of 3.5 minutes and a standard deviation of 1 minute, find the point in the distribution that 75.8% of the MBA students exceed when...
January 19, 2012 by mehul

math
Assume that the average annual salary for a worker in the United States is $30,500 and that the annual salaries for Americans are normally distributed with a standard deviation equal to $6,250. Find the following: (A) What percentage of Americans earn below $19,000? (B) What ...
October 25, 2012 by Jen

Math
Assume that the average annual salary for a worker in the United States is $30,500 and that the annual salaries for Americans are normally distributed with a standard deviation equal to $6,250. Find the following: (A) What percentage of Americans earn below $19,000? (B) What ...
October 28, 2012 by Michael

Statistics
The Amount of filling a half-liter (500ml)soft drink bottle is normally distributed. The process has a standard deviation of 5ml. The mean is adjustable. A. Where should the mean be set to ensure a 95% probability that a half-liter bottle will not be under filled? B. A 99% ...
April 11, 2014 by KT

Math/Probability/Statistics
Find the expected value and the standard deviation in the following raffle: Value Tickets Grand Prize: $2,000.00 1 Second Place Prize: $800.00 20 Third Place Prize: $40.00 60 Fourth Place Prize: $30.00 300 Total Number of Tickets Sold: 10000
October 22, 2015 by Anonymous

algebra 2b
A simple random sample of 50 adults was surveyed, and it was found that the mean amount of time that they spend surfing the Internet per day is 54.2 minutes, with a standard deviation of 14.0 minutes. What is the 99% confidence interval (z-score = 2.58) for the number of ...
May 17, 2016 by kevin

Statistics
is the standard deviation a measure of the center or distribution... my teacher told me center i read the article and i\'ve been lead to believe its a measure of the distribution not the center... if it is a measure of the center how is it? I think it\'s a measure of the ...
August 30, 2009 by Statistics

Stats
National Packing Materials Company claims its X20 box can hold loads up to at least 80 pounds. Smith Widget Company has been using the boxes for one year and feels the boxes fail at lighter loads. Hearing the complaints from Smith, the lead engineer for National Packaging ...
September 14, 2008 by Arthur

Statistics
A purchasing agent for a trucking company is shopping for replacement tires for their trucks from two suppliers. The suppliers' prices are the same. However, Supplier A's tires have an average life of 60,000 miles with a standard deviation of 10,000 miles. Supplier B's tires ...
December 17, 2009 by Tykrane

Statistics
A purchasing agent for a trucking company is shopping for replacement tires for their trucks from two suppliers. The suppliers' prices are the same. However, Supplier A's tires have an average life of 60,000 miles with a standard deviation of 10,000 miles. Supplier B's tires ...
December 17, 2009 by Tykrane

Statistics
1. A simple random sample of FICO credit rating scores is listed below: 714 751 664 789 818 779 698 836 753 834 693 802 a. Find range, variance, and standard deviation. b. As of this writing, the mean FICO score was reported to be 678. Based on these results, is a FICO score ...
October 5, 2013 by Shannon

algebra
Three firms carry inventories that differ in size. Firm A's inventory contains 2000 items, firm B's inventory contains 5000 items, and firm C's inventory contains 10,000 items. The population standard deviation for the cost of the items in each firm's inventory is = 144. A ...
December 30, 2014 by Anksuh

statistics
drug company promises to help people lose at least 3 pounds per week. 15 people use the drug. they lose an average of 2.8 lbs per week with a standard deviation of .5lbs. is this a left tail or right tail and why?
June 11, 2012 by Anonymous

Statistics
Please can some one help me with the following: A fisherman finds that approximately 17% of all his fish go bad by the time he takes them to the market. The fisherman catches 1,000 fish. A. How many will go bad by the time he takes them to the market? B. Find the standard ...
December 25, 2012 by Alia

Statistics
Please can some one help me with the following: A fisherman finds that approximately 17% of all his fish go bad by the time he takes them to the market. The fisherman catches 1,000 fish. A. How many will go bad by the time he takes them to the market? B. Find the standard ...
December 26, 2012 by Alia

Statistics
32% of adult internet users have purchased products or services online. For a random sampling of 200 adult users, find the mean, variance and standard deviation for the number who have purchased goods or services online?
March 17, 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
SAT I scores around the nation tend to have a mean scale score around 500, a standard deviation of about 100 points, and are approximately normally distributed. What SAT I score within the population would have a percentile rank of approximately 97.5? Show all work as to how ...
September 29, 2012 by Anonymous

Statistics
Scores on a visual perception test are normally distributed with a mean of 2020 and a standard deviation of 250. a)If one subject is randomly selected and tested, find the probability of a score greater than 1800 b)if 50 subjects are randomly selected and tested fid the ...
March 21, 2013 by Sunshine

statistics
Scores on a visual perception test are normally distributed with a mean of 2020 and a standard deviation of 250. a)If one subject is randomly selected and tested, find the probability of a score greater than 1800 b)if 50 subjects are randomly selected and tested fid the ...
March 21, 2013 by Sunshine

math
A study conducted by a TV station showed the number of televisions per household and the corresponding probabilities for ecach. Find the mean, variance, and standard deviation. (in table) Number of televisions 1 2 3 4 Probability P(X) 0.32 0.51 0.12 0.05 If you were talking a ...
April 10, 2013 by Lesley

Math
The average monthly mortgage payment including principal and interest is $982 in the United States. If the standard deviation is approximately $180 and the mortgage payments are approximately normally distributed, find the probability that a randomly selected monthly payment ...
April 10, 2013 by Lesley

statistics
A scale measuring prejudice has been administered to a large sample of respondents. The distribution of scores is approximately normal with a mean of 31 and a standard deviation of 5. What percentage of sample had scores 1) Below 20 2) Above 40 3) Above 20 4) Below 40 5) Below...
September 30, 2011 by Brady

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
women's heights are normally distributed with a mean 63.1 in and standard deviation of 2.5. A social organization for tall people has a requirement that women must be at least 69in tall. What percentage of woman meet that requirement? The percentage of woman that are taller ...
June 1, 2013 by Jenn

business statitics
a) The mean lifetime of a sample of 100 light tubes produced by a company is found to be 1570 hours with standard deviation of 80 hours. Test the hypothesis that the mean lifetime of the tubes produced by the company is 1600 hrs. (7 marks)
October 27, 2015 by john

statistics (7)
The average cost per night of a hotel room in New York City is $273 (SmartMoney, March 2009). Assume this estimate is based on a sample of 45 hotels and that the sample standard deviation is $65. a. With 95% confidence, what is the margin of error (to 2 decimals)? b. What is ...
April 23, 2014 by Vanessa

statistics (7)
The average cost per night of a hotel room in New York City is $273 (SmartMoney, March 2009). Assume this estimate is based on a sample of 45 hotels and that the sample standard deviation is $65. a. With 95% confidence, what is the margin of error (to 2 decimals)? b. What is ...
April 26, 2014 by Mia

Statistics
Some IQ scores are standardized with a mean of 100 and a standard deviation of 16. Using the 68-95-99.7 Rule, Determine: 1. What percent of people would have an IQ score of no more than 68. (2).What percent of people would have an IQ score of 100 or above.
February 25, 2008 by Math help

Algebra
Mr. Smith has 100 students in his Algebra classes. The grades of a quiz are normally distributed with a mean of 70 and a standard deviation of 4. Sally claims that 75 students scored between 66 and 74 on this quiz. Given that this is normally distributed, is Sally correct?
March 2, 2015 by Help is needed

Stats
On Tuesday September 27, 2016 the high temperature increased to 36.7 degrees Celsius (98 degrees Fahrenheit). What is the probability that we observe a temperature of 36.7 degrees Celsius or higher given that the average temperature is 27 degrees Celsius with a standard ...
October 8, 2016 by Kleena

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

High School Math
I'm reviewing for my final exam can anyone give me some tips on this I know what this means but I just to know someone eles opinion. Thanks Under what conditions might it be appropriate to use the mean? Median? Mode? When the median and mean are substantially different, what ...
July 14, 2009 by Selena

statistics
The time that it takes a randomly selected job applicant to perform a certain task has a distribution that can be approximated by a normal distribution with a mean value of 120 sec and a standard deviation of 25 sec. The fastest 10% are to be given advanced training. What task...
April 8, 2011 by chels

Math 540
The Department of Management Science at Tech has sampled 250 of its majors and compiled the following frequency distribution of grade point averages (on a 4.0 scale) for the previous semester. GPA Frequency 0-0.5 1 0.5-1.0 4 1.0-1.5 20 1.5-2.0 35 2.0-2.5 67 2.5-3.0 58 3.0-3.5 ...
May 16, 2011 by Cassie

Stats
The time that it takes a randomly selected job applicant to perform a certain task has a distribution that can be approximated by a normal distribution with a mean value of 150 sec and a standard deviation of 20 sec. The fastest 10% are to be given advanced training. What task...
October 2, 2013 by B

statistics
Reading placement scores for a particular college are normally distributed with a mean of 72 and a standard deviation of 7. a) draw a sketch of the reading placement scores for students at this college. be sure to mark the mean and also to mark one and two standard deviations ...
June 3, 2012 by whitney

12th grade Math-statistics
The annual sales, in millions, for 28 toy department stores is listed. A)Calculate the mean and standard deviation of the data. Answer to the nearest tenth. B) Calculate the percent of sales to the nearest whole number, that are: i)within one SD of the mean ii)within two SD of...
December 12, 2008 by Jodine

Math
The average daily high temperature for the month of September in Los Angeles is 27 degrees Celsius (81 degrees Fahrenheit) with a standard deviation of 2.78 degrees Celsius. How hot are the hottest 10.03% days during September in Los Angeles? Provide your answer to two decimal...
October 8, 2016 by Kleena

ELEMENTARY STATISTICS
50 MATH PROFESSORS WERE ASKED HOW LONG IT TAKES TO GRADE A STUDENT'S HOMEWORK ASSIGNMENT. THE MEAN GRADING TIME FOR THE SAMPLE WAS 36.2 MINUTES WITH A STANDARD DEVIATION OF 4.8 MINUTES. WHAT IS THE 99% CONFIDENCE INTERVAL FOR THE MEAN GRADING TIME OF ALL MATH PROFESSORS?
November 25, 2011 by DARLENE

statistics
The number of hours that college students sleep on a week night is approximated by a normal curve with a mean of 7 hours and a standard deviation of 1.7 hours. Answer the question below using a z table: On a week night, what percentage of students sleep between 5 and 10 hours
August 18, 2014 by Anonymous

Statistics
Suppose that hours of sleep per night for single adults between 30 and 40 years of age are normally distributed with a mean of 6.7 hours and a standard deviation of 1.1 hours. What proportion of adults sleep longer than 4.5 hours per night? (Report to 3 decimal places.)
November 26, 2014 by Beth

Math
The systolic blood pressures of a group of 18-year-old women are normally distributed with a mean of 120 mmHg and a standard deviation of 12 mmHg. What percentage of women in this group have a systolic blood pressure between 108 mmHg and 132 mmHg?
September 20, 2015 by Jacqueline

Statistics
The ratio of brown M&M’s in a bag is stated by the candy company to be 56%. If a random sample of 500 bags is selected, determine the probability that the sample proportion of random bags of M&M’s selected has a percentage of brown between 51% and 59% p=.56 standard ...
November 23, 2015 by Kim

math
Suppose the yearly rainfall totals for a some city follow a normal distribution, with mean of 18 inches and standard deviation of 6 inches. For a randomly selected year, what is the probability, P, that total rainfall will be in each of the following intervals? (Round all ...
October 17, 2010 by Anonymous

statistics
This is what my teacher gave us I guess he want us to figture out the question. cost/mile 0.08 normal distribution means=.08 standard deviation=0.2 Car life 5 uniform distribution( minmun=2, max=8 annual milage =900 triangular distribution(min=3700 most likely =9000 max=14500 ...
July 13, 2011 by elizabeth6

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

math
find the standard deviation for the given data. Round your answer to one more decimal place than original data. (9,7,13,24,32,45,47) I get 16.62041 but how do I round my answer to one or more decimal places? I am a little lost.
November 19, 2009 by Marie

statistics
Suppose that the ages of students at a particular university average 26 years with a standard deviation of 2.8 years. Consider the sampling distribution of the sample mean age of students in a sample of n = 49. The mean of the sampling distribution is __________
July 9, 2014 by Taylor

Math
A sample of 120 bags of potatoes produced by a factory was found to have a mean weight of 2.47 kg and a standard deviation of 0.12 kg. Obtain a 95% confidence interval for the mean weight of all bags of potatoes produced by the factory.
October 24, 2016 by Grace

Chemistry
Table sugar consists mostly of sucrose, C12H22O11. The standard enthalpy of combustion for sucrose is the standard state delta H for the reaction: C12H22O11 + 12 O 2 ---> 12 CO2 + 11 H2O Calculate this standard state delta H. Give answer in units of kJ to five significant ...
December 3, 2016 by Eli

statistics
Consider the test of hypothesis for the equality of two population means. The sample data from the first population is: n = 10, x-bar = 52.4, s = 5. The sample data from the second population is: n = 8, x-bar = 48.2, s = 6. Both variables are normally distributed and the ...
March 27, 2015 by Anonymous

statistics
The body temp of normal healthy persons are normally distributed with a mean of 98.2 degrees F and a standard deviation od .62 degree F. If we define a fever to be a body temp above 100 degrees F, what percentage of normal and healthy person would be considered to have a fever?
May 19, 2013 by Anonymous

Statistics
A private medical clinic wants to estimate the true mean annual income of its patients. The clinic needs to be within $100 of the true mean. The clinic estimates that the true population standard deviation is around $2,100. If the confidence level is 95%, find the required ...
April 15, 2012 by Jason

statistics
An 8th grade history teached studied the statistics for her mid-term exam. The average grade for the mid-term was 84 points, and the standard deviation was 8 points. The Z-score for a student who scores 90 on the exam is: 84-90/8= -0.75
June 3, 2014 by Jodi

MATH HELP
The amount of fill (weight of contents) put into a glass jar of spaghetti sauce is normally distributed with mean ì = 843 grams and standard deviation of ó = 9 grams (d) Find the mean of the x distribution. (Give your answer correct to the nearest whole number.) 843 Was my ...
June 19, 2013 by TOM7

Pre-calculus
A set of data is normally distributed with a mean of 500 and standard deviation of 40. a). What percent of the data is between 460 and 540? P(460<x<540)=P(-1<z<1) =0.8413-0.1587 =0.6826 b). Find the probabilty that a value selected at random is less than 420. P(x&...
January 16, 2009 by Mary

Math
A certain type of thermal battery for an airplane navigation device backup power has a mean life of 300 hours with a standard deviation of 15 hours. Assume a normal distribution of backup power device lives. What proportion of these batteries can be expected to have lives of ...
October 6, 2009 by Anonymous

Math
A certain type of thermal battery for an airplane navigation device backup power has a mean life of 300 hours with a standard deviation of 15 hours. Assume a normal distribution of backup power device lives. What proportion of these batteries can be expected to have lives of ...
October 7, 2009 by Anonymous

statistics
the average weekly earnings of a production worker were $424. to know if wages, on average, have gone up since that time. To test this, you sample 64 production workers, and determine that their average salary is $432.69, with a sample standard deviation of $33.90. Use a 0.05 ...
July 18, 2010 by Anonymous

Math/Statistics
The mean starting salary for graduates in the spring of 2004 was $36,280. Assume that the distribution of starting salaries follows the normal distribution with a standard deviation of $3,300. What percent of the graduates have starting salaries between $35,000 and $40,000? a...
November 29, 2010 by Dave

statistics
the admissions policy at a certain university requires that incoming students score in the upper 20% on a standardized test. if the mean score on the test is 510 and the standard deviation of the scores is 80, what is the minimum score that a student can earn on the test to ...
December 15, 2011 by Anonymous

statistics
the admissions policy at a certain university requires that incoming students score in the upper 20% on a standardized test. if the mean score on the test is 510 and the standard deviation of the scores is 80, what is the minimum score that a student can earn on the test to ...
December 15, 2011 by Anonymous

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
An accelerated life test on a large number of type-D alkaline batteries revealed that the mean life for a particular use before they failed is 19.0 hours. The distribution of the lives approximated a normal distribution. The standard deviation of the distribution was 1.2 hours...
April 11, 2014 by Ryan

Math
This is a question on a study guide for a test tomorrow. How do you do it? Please help According to the Federal Highway Administration, teenage males drive an average of 10,718 miles each year. Assume the mileage totals are normally distributed with a standard deviation of ...
May 24, 2011 by David

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