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April 21, 2015

Search: Standard Deviation-What?

Number of results: 8,685

statistics
The typical amount of sleep per night for undergraduate college students has a bell shaped distribution with a mean of 7 and a standard deviation of 1.90 hours. Based on this distributional information we can conclude that at least 95 % of this population sleep ...
September 27, 2013 by jennifer

Algebra II
The grades on the last math exam had a mean of 88%. Assume the population of grades on math exams is known to be normally distributed with a standard deviation of 6. What percent of students earn a score between 72% and 90%? (5 points) 0.6255 0.5843 0.6754 0.5346
May 23, 2014 by Pewdiepie

Stat
Thirty randomly selected students took the calculus final. If the sample mean was 89 and the standard deviation was 6.2, construct a 99% confidence interval of the mean score of all students. Assume that the population has a normal distribution. what formula do i use????
September 30, 2014 by Billy

six sigma
If the mean value of the weight of a particular brand of dog food bag is 20.6 pounds and the standard deviation is 1.3, assume a normal distribution and calculate the percentage of bags that falls below the lower specification value of 19.7 pounds.
November 26, 2014 by stansler

Stats
Find probability that a randomly selected TV will have replacement time less than 6 yrs. mean is 8.2 yrs standard deviation is 1.1 then provide warranty of 1% will be replaced what is the time length of the warranty
November 17, 2008 by Valerie

statistics
If 80% of the applicants are able to pass a driver's proficiency road test, find the mean, variance, and standard deviation of the number of people who pass the test in a sample of 300 applicants.
October 1, 2010 by jean

Statistics
the scores of a standardized test are normally distribution with a mean of 312 and a standard deviation of 68. The bottom 40% of scores are designed 'Need improvement'. What is the cutoff score for those who 'Need improvement'?
May 4, 2011 by Lauran

math
The weight of lolly pops in a box is normally distributed with a mean of 5kg and a standard deviation of 0.1kg. What is the probability that a randomly selected box of lolly pops weighs between 5.03 and 5.16 kg?
May 31, 2011 by TUVALU

statistics
FB: Attendance at a university's basketball games follows a Normal distribution with mean ě = 8,000 and standard deviation ó = 1,000. 60% of all games will have more than _______ people in attendance.
February 7, 2012 by Anonymous

STATISTICS
the percentage rates of home ownership for 8 randomdomly selected states are listed below. Estimate the population variance and standard deviation for the percentage rate of home ownership with 99% confidence. 66.0 75.8 70.9 73.9 63.4 68.5 73.3 65.9
April 17, 2013 by Paula

STATISTICS
the percentage rates of home ownership for 8 randomly selected states are listed below. Estimate the population variance and standard deviation for the percentage rate of home ownership with 99% confidence. 66.0 75.8 70.9 73.9 63.4 68.5 73.3 65.9
April 19, 2013 by Paula

statistics
Assume that body temperatures of healthy adults are normally distributed with a mean of 98.2°F and a standard deviation of 0.62°F. Find the 90th percentile of the sample mean body temperatures for samples of size 16.
May 7, 2013 by ali awan

statistics
Suppose that the average score on the GMAT exam is 500 and that the standard deviation of all scores is 100 points. You would expect approximately 95% of all GMAT scores to be between
July 24, 2013 by thomas

statistics
The scores for standardized test are normally distributed with a mean of 300 and standard deviation of 39. If the test is given to 700 students, how many are expected to have scores between 300 and 378.
July 25, 2013 by melissa

math
it is claimed that the average age of employees in a large company is 50. a sample of 36 employees is taken and the average age was 49. the standard deviation of the population was 5. use a level of significance of 0.5. what do you think of the claim?
July 30, 2013 by marissa

math
kris scored 630 points on a particular section of a CPA exam for which the score were normally distributed with a mean of 600 points and a standard deviation of 75 points. At a differenttime, kerry scored 540 points on the same section, for which scores were normally ...
April 12, 2011 by kaleb

math
kris scored 630 points on a particular section of a CPA exam for which the score were normally distributed with a mean of 600 points and a standard deviation of 75 points. At a differenttime, kerry scored 540 points on the same section, for which scores were normally ...
April 13, 2011 by shirley

finite math
kris scored 630 points on a particular section of a CPA exam for which the score were normally distributed with a mean of 600 points and a standard deviation of 75 points. At a differenttime, kerry scored 540 points on the same section, for which scores were normally ...
April 14, 2011 by margie

statistics
A psychologist interested in political behavior measured the square footage of the desks in the official office of four U.S. governors and of four chief executive officers (CEOs) of major U.S. corporations. The figures for the governors were 44, 36, 52, and 40 square feet. The...
June 29, 2009 by Gregory

statistics
5. Each year, a national achievement test is administered to 3rd graders. The test has a mean score of 100 and a standard deviation of 15. If Jane's z-score is 1.20, what was her score on the test?
September 2, 2011 by xiomara

statistics
Suppose that 30% of all telephone calls at work are for personal reasons. If a random sample of 15 is taken, let X be the number of personal calls. The standard deviation of the # of personal calls is:
June 5, 2013 by Anonymous

Statistics
For a population with a mean of µ=60 and standard deviation of Ợ=24, find the z=score corresponding to each of the following samples a. M=63 for sample of n=16 scores b. M=63 for sample of n=36 scores c. M=63 for sample of n=64 scores
December 13, 2013 by Lyndyc

Stats
A survey was conducted to determine the number of hours people listen to the radio. While most of the listening is in the car, it turns out that the mean is 2.5 hours with a standard deviation of 0.75 hours. Find the probability that the sum of 100 values is less than 240.
December 3, 2012 by Alley

statistics
The distribution of scores on a standardized aptitude test is approximately normal with a mean of 490 and a standard deviation of 95. What is the minimum score needed to be in the top 25% on this test? Carry your intermediate computations to at least four decimal places, and ...
May 6, 2012 by SHelia

statics
The times for completing one circuit of a bicycle course are normally distributed with a mean of 81.7 minutes and a standard deviation of 8.6 minutes. An association wants to sponsor a race and provide prizes for the top (that is, fastest) 15% of riders. Where should they ...
July 10, 2012 by john

math
The times for completing one circuit of a bicycle course are normally distributed with a mean of 81.7 minutes and a standard deviation of 8.6 minutes. An association wants to sponsor a race and provide prizes for the top (that is, fastest) 15% of riders. Where should they ...
July 12, 2012 by john

math
The times for completing one circuit of a bicycle course are normally distributed with a mean of 81.7 minutes and a standard deviation of 8.6 minutes. An association wants to sponsor a race and provide prizes for the top (that is, fastest) 15% of riders. Where should they ...
July 12, 2012 by john kay

Statics
In designing an experiment, a psychologist is willing to assume that the underlying distribution for the time to learn a list of words is approximately normal with a standard deviation of 40 seconds. He wants to be 95% sure that the maximum error of his estimate of the mean ...
December 1, 2012 by Heather

algebra
i need help: A national achievement test is administered annually to 9th graders. The test has a mean score of 100 and a standard deviation of 15. If John’s z-score is 1.20, what was his score on the test?
November 19, 2013 by mufasa

Statistics
A college admissions officer takes a simple random sample of 103 entering freshmen and computes their mean mathematics SAT score to be 493. Assume the population standard deviation is 112. What is the lower bound of the 99% confidence interval? Round your answer to the nearest...
June 26, 2013 by Please help me work out this problem!!!

statistics
Do you want to own your own candy store? Wow! With some interest in running your own business and a decent credit rating, you can probably get a bank loan on startup costs for franchises such as Candy Express, The Fudge Company, Karmel Corn, and Rocky Mountain Chocolate ...
November 5, 2012 by noell

stats
sample of n=64 scores is obtained from population with standard deviation =15 sample mean is 10 pts greater than the poulation mean what is zscore for sample mean
March 22, 2013 by tita

statistics
2. The results of a recent survey indicate that the average new car costs $23,000, with a standard deviation of $3,500. The price of cars is normally distributed. a. What is a Z score for a car with a price of $ 33,000?
September 11, 2010 by Anonymous

Phoenix of Arizona
If 80% of the applicants are able to pass a driver's proficiency road test, find the mean, variance, and standard deviation of the number of people who pass the test in a sample of 300 applicants.
February 17, 2012 by Jayda

statistics
Varsity team try out. Assume the distribution of heights to be normal w/a mean of 64inches & standard deviation of 4 inches. only 15 students passed. how many students joined the try out?
February 22, 2012 by mike

statistics
The life span of the battery pack is known to be Normally distributed with a mean of 250 hours and a standard deviation of 20 hours. How to find the percentage of the battery packs lasting more than 250 hrs.
May 6, 2012 by noe

statistics
The Intelligence Quotient (IQ) test scores for adults are normally distributed with a mean of 100 and a standard deviation of 15. What is the probability we could select a sample of 50 adults and find the mean of this sample is between 95 and 105?
November 11, 2012 by Trev

statistics
The winning team's score in 11 high school basketball games were recorded. If the sample mean is 9.5 points and sample standard deviation is 0.25 points, what is the 98% confidence interval for the true population mean?
November 24, 2012 by Christi

Steve help!
10,000 students took a math test. If there average score was 40 with standard deviation of 10, how many students must have scored between 20 and 40 marks? 3,772 2,227 5,000 3,334 4,772
November 28, 2012 by Tina

stats
scores on a university examination are normally distributed with a mean of 68 and standard deviation of 9. What percetnage of students scores above 77? The answer is 16% according to the professor that is correct. But I don't understand how the professor got to that answer.
March 14, 2013 by Anonymous

statistic
The random variable x represents the number of boys in a family with three children. Assuming that births of boys and girls are equally likely, find the mean and standard deviation for the random variable x.
August 20, 2013 by Kim

statistics
A random sample of 100 students from a high school was selected. If a 98% confidence interval estimate for the mean age of students is calculated to be 14.2511 to 14.9489, then the standard deviation of the sample mean is?
November 17, 2013 by zac

math
A study of 60 bolts of carpet showed that their average length was 180 yards. The standard deviation of the population is 6 yards. Which of the following is the 99% confidence interval for the mean length per bolt of carpet?
April 14, 2014 by hassan

math
Studies shown that gasoline use or compact cars sold in the U.S. is normally distributed, with a mean of 25.5 mpg and standard deviation of 4.5 mpg. Find the range of mileage for the middle 60% of compact cars.
November 18, 2014 by sarah

statistics
In a population of exam scores, a score of x=88 corresponds to z=+2.00 and a score of x=79 corresponds to z=-1.00. Find the mean and standard deviation for the population.
February 5, 2008 by Tegan

Math
In a population of exam scores, a score of X=88 corresponds to z= +2.00 and a score of X=79 corresponds to z= -1.00. Find the mean and standard deviation for the population.
September 25, 2009 by Jen

statistics
In a population of exam scores, a score of X=88 corresponds to z= +2.00 and a score of X=79 corresponds to z= -1.00. Find the mean and standard deviation for the population.
September 25, 2009 by Jen

AP Statistics
if the probability of a dribbling drummer is .38, find the standard deviation of the dribbling drummers drumming for the twelve drummers drumming
January 6, 2010 by Belle

statistics
In a population of exam scores, a score of X = 48 corresponds to z = +1.00 and a score of X = 36 corresponds to z = -0.50. Find the mean and standard deviation of the population.
March 17, 2010 by Teresa

Stats
A loaf of bread is normally distributed with a mean of 22 ounces and a standard deviation of .5 ounces. What is the probability that a loaf of bread is < 20.75
March 30, 2010 by Anonymous

statistics
In a population of exam scores,a score of X= 48 corresponds to z= 1 and a score of X= 36 corresponds to z= -.50. Find the mean and standard deviation for the population?
March 9, 2012 by Amy

Math
On a recent math exam, Alex received a score of 92%. His z-score is positive 2. If the mean for the exam is 84, what is the standard deviation?
April 16, 2013 by James Jones

Probability
A department store has determined that 25% of all their sales are credit sales. A random sample of 75 sales is selected and the proportion of credit sales in the sample is computed. a) What is the probability that the same proportion will be greater than 0.34? In a random ...
November 23, 2006 by Janice

Finite Math
If the life in years, of a television set is normally distributed with a mean of 46 years and a standard deviation of 4 years, what should be the guarantee period if the company wants less than 3% of the television sets to fail while under warranty?
February 13, 2010 by Maria

math
The heights in inches of 18 randomly selected adult males in LA are listed as: 70, 69, 72, 57, 70, 66, 69, 73, 80, 68, 71, 68, 72, 67, 58, 74, 81, 72. Display the data in a stem-and-leaf plot. 1. Find the mean. 2. Find the median. 3. Find the mode. 4. Find the range. 5. Find ...
May 19, 2010 by Bill

Statistics
The heights in inches of 14 randomly selected adult males in LA are listed as: 71, 67, 70, 59, 71, 68, 67, 71, 80, 68, 74, 69, 72, 68. 1. Display the data in a stem-and-leaf plot. 2. Find the mean. 3. Find the median. 4. Find the mode. 5. Find the range. 6. Find the variance...
September 20, 2010 by Shawna

Math: Statistics
A study of elephants wishes to determine the average weight of a certain subspecies of elephants. The standard deviation of the population is 2,014 pounds. How many elephants need to be weighed so we can be 93% confident to be accurate within 325 pounds?
November 17, 2010 by Anonymous

statistics
A company that manufacturers bookcases finds that the average time it takes an employee to build a bookcase is 23 hours with a standard deviation of 8 hours. A random sample of 64 employees is taken. What is the likelihood that the sample mean will be 18 hours or more?
March 6, 2012 by Diane

Math
For a class test, the mean score was 65, the median score was 71 and sthe standard deviation of the scores was 7. The teacher decided to add 5 points to each score due to a grading error. Which of the folloiwng must be true for thenew scores? TH
August 15, 2011 by Gail

statistics
The heights in inches of 14 randomly selected adult males in LA are listed as: 71, 67, 70, 59, 71, 68, 67, 71, 80, 68, 74, 69, 72, 68. 1. Display the data in a stem-and-leaf plot. 2. Find the mean. 3. Find the median. 4. Find the mode. 5. Find the range. 6. Find the variance. ...
November 13, 2011 by Anonymous

stats
blood cholesterol level of all men age 20-24 follows N(188,41) where the units for the men and standard deviation are in mg/dl. what is the probability that the sample mean takes a value between 185 and 191 if we sample 1000 men
October 12, 2012 by sam

statistics
A group of 49 randomly selected construction workers has a mean age of 22.4 years with a standard deviation of 3.8. According to a recent survey, the mean age should be mu=21.9. Test this hypothesis by constructing a 98% confidence interval for the population mean.
November 19, 2013 by Cheryl

statistics
the average act score submitted to a certain university is 26. to be eligible for admission, a student must score in the top 6% of applicants. if the scores are normally distributed with a standard deviation of 2.4, what is the minimum score needed to be considered for admission?
March 21, 2014 by roger

Statistics
The life of a blood pressure monitor has a normal distribution with an average of 40 years and a standard deviation of one year. What should the warranty be to replace a malfunctioning monitor with - if the company does not want to replace more than 1% of all the monitor. ...
June 6, 2014 by Ann

Math
The weekly salaries of 100 recent graduates of a private women's college are normally distributed with a mean of $600 and a standard deviation of $80. Determine the interval about the sample mean that has a 1% level of confidence. Use t=2.58 I don't know. 600/sqrt100 60 80+-2....
October 1, 2008 by Anonymous

Math
The weekly salaries of 100 recent graduates of a private women's college are normally distributed with a mean of $600 and a standard deviation of $80. Determine the interval about the sample mean that has a 1% level of confidence. Use t=2.58 I don't know. 600/sqrt100 60 80+-2....
October 1, 2008 by Anonymous

Statistics
The amount of fill(weight of contents)put into a glass jar of spaghetti sauce is normally distributed with mean=850g and standard deviation=8g.the probability that a random sample of 24 jars has a mean weight greater than 848g is?need help
March 23, 2011 by Joel

stats ( please check)
6. X has a normal distribution with a mean of 80.0 and a standard deviation of 3.5. Find the following probabilities: (A) P(x < 77.0) (B) P(75.0 < x < 85.0) (C) P(x > 85.0) (Points : 6) I think I have the first two but I am stumped on the third one. Thank you for ...
July 24, 2011 by Celest

statistics
In a preliminary study, the sample standard deviation for the duration of a particular back pain suffered by patients was 18.0 months. How large a random sample is needed to construct a 90% confidence interval so that an estimate can be made within 2 months of the actual duratio
August 2, 2011 by joe

statistics
The SAT scores of a certain population of students are approximatley normally distributed with a mean and standard deviation of 1000 and 200 points, respectively. the probabilalty that a student selected at random from the population has an SAT score between 800 and 1200 is?
February 28, 2013 by ken

math
A sample of size 100 is chosen from a normally distributed mean,(µ) and standard deviation 60. A researcher has made the statement as follow to conclude that value of µ: " reject H0:µ= 80 and accept H1: µ < 80. if x̅ < 68 " a) if the significant level used is ∝...
October 17, 2013 by sree

CRJ303-Statistics question
Re-worded from the "Study Questions" part of Chapter 5 from this site: "Student Study Site for Essentials of Social Statistics for a Diverse Society" Please show the steps for each question "When the Scholastic Aptitude Test (SAT) - now known as the Scholastic Assessment Test...
December 7, 2012 by Michael

statistics
14.how would you describe this set of data? In other words, how would you describe the “average” score (mean, median or mode and why)? How would you describe the variability (range, standard deviation, or both, and why)? 3 3 3 4 3 2 4 2 3 4
November 23, 2010 by Lola

Math
*Sigh* Can someone explain to me how I would work thru this problem? An honest coin tossed n=3600 times. Let the random variable Y denote the number of tails tossed. (a) find the mean and the standard deviation of the distribution of the random variable Y (b) what are the ...
October 5, 2006 by SherylA

statistics
The average price for new mobile homes is known to be distributed with a standard deviation of 350. if a random sample of 49 homes resulted in a sample mean of 38500, obtain a 90% confidence interval on the population mean.
March 26, 2009 by April

statistics
Assume that blood pressure readings are normally distributed with a mean of 123 and a standard deviation of 9.6. If 144 people are randomly selected, find the probability that their mean blood pressure will be less than 125
November 8, 2011 by Anonymous

statistics
Determine the probability that a sample of 49 boxes will have a mean weight below 365grams. past records show that the population mean is 368 grams and the population standard deviation is 7. the probability will be between
November 30, 2011 by wanda

Statistics
The weights of trout in a certain river follow a normal distribution with mean 3 pounds and standard deviation 0.8 pounds. What proportion of trout weigh between 3.2 pounds and 4.8 pounds? a.) .3891 b.) .9972 c.) .9452 d.) .5865
December 1, 2011 by Jay

statistics
what happens to the width of our confidence interval for mu if we increase the sample size but keep the confidence level the same ? a. it increases b. it stays the same c. it decreases d. it depends on the sample mean and standard deviation
December 6, 2011 by jen

Statistics
suppose a random sample of 360 students is drawn form a population of students. Among sampled, the average IQ score is 12 with standard deviation of 3. What is the upper confidence limit of the 95% confidence interval of the population
March 14, 2012 by Arona Basuti

Statistics
The distribution of heights of women aged 20 to 29 is approximately Normal with mean 63.6 inches and standard deviation 3 inches. The height (± 0.1 inch) of the middle 68% of young women falls between a low of inches and a high of inches.
September 4, 2012 by Stacie

statistics
supposed that the average weight loss for someone on a diet is 15 pounds with the standard deviation of 4 pounds. a sample of 18 adults enrolled a sswp have a mean weight loss of 15.83. using 0.01 level of significance.
October 2, 2012 by jericho

statistics
5. What happens to the width of our confidence interval for m if we increase the sample size but keep the confidence level the same? A) It increases. B) It decreases. C) It stays the same. D) It depends on the sample mean and standard deviation.
May 8, 2013 by ali awan

statistics
Assume that blood pressure readings are normally distributed with a mean of 123 and a standard deviation of 9.6. If 144 people are randomly selected, find the probability that their mean blood pressure will be less than 125.
October 14, 2013 by florence

statisticss
The time taken by a man to deliver milk is normally distributed with, mean 12 minutes and standard deviation 2 minutes. He delivers milk everyday estimate the probability that he takes. (a) longer than 17 minutes (b) between 9 and 13 minutes
July 8, 2014 by Heidi

Probability
Please help.. Find the probability of getting 2 hearts if the cards are drawn from a regular deck and the first card is not replaced. A true/false quiz consists of twenty questions. If a student answers the twenty questions by making random guesses, what is the probability of ...
December 10, 2006 by Mary

math
It is equally probable that stock A will have a +10% or -10% rate of return The only other possibility is that it will return 0%.The probability of 0% is twice that for a return of +10%. What is the expected return and Standard deviation of the return for stock A?
September 24, 2014 by Anonymous

Statistics
30 randomly selected cans of Coke are measured for the amount of cola in ounces. The sample values have a mean of 12.18 ounces and a standard deviation of 0.118 ounces. The 99% confidence interval is ( ounces, ounces). Round each result to two decimal places.
November 9, 2013 by Katie

Chemistry
When 0.312g of glucose was burned in a bomb calorimeter (heat capacity 641 J/K) the temperature rose by 7.739 K. Calculate the standard enthalpy of combustion and the standard internal energy of combustion. I've calculated the standard enthalpy but am unsure of how to go about...
September 25, 2012 by Kalli

math
The average selling price of homes in a certain city is $356,300. Assume the variable is normally distributed with a standard deviation of $64,600. If 396 homes are for sale, how many homes will sell for more than $325,000? (Round up to the next whole number.)
November 28, 2011 by Jennifer

statistics
A company produces batteries whose lifetimes are normally distributed with a mean of 100 hours. It is known that 90% of the batteries last at least 40 hours. (i). Estimate the standard deviation lifetime. (3 marks) (ii). What percentage of batteries will not last 70 hours?
April 26, 2013 by Ravi

Math - Pre-Algebra
44) A financial institution wishes to estimate the mean balances owed by its credit card customers. The population standard deviation is estimated to be $300. If a 98 percent confidence interval is used and an interval of ±$75 is desired, how many cardholders should be sampled...
August 30, 2010 by BC

math
at one high school the mean time for running the 100-yard dash is 15.2 seconds with a standard deviation of 0.9 seconds. The times are very close approximated by a normal curve. Find the percent of times that are: between 15.2 and 16.1 seconds
July 14, 2008 by Leanne

statistics
The amount of snow fall falling in a certian mountain range is normally distributed with a mean of 83 inches, and a standard deviation of 16 inches. What is the probability that the mean annual snowfall during 64 randomly picked years will exceed 85.8 inches?
March 4, 2009 by kasey

math
Find the z-score for the given raw score, mean, and standard deviation. Assume a normal probability distribution score = 15, ě = 16 , and ó = 2 Could you show me how to do this. My instructor has tried but I just don't understand how to do it and I have several questions to ...
August 23, 2009 by sam

Statistics
A lorry carries heavy cartons of goods. The weights of theses cartons are distributed about a mean of 100 kg and with a standard deviation of 7 kg. Find how many cartons the lorry can carry so that the probability of the total load exceeding 4500 kg is less than 0.5.
April 18, 2012 by Sniper619

Q. Research
3. Bob takes an online IQ test and finds that his IQ according to the test is 134. Assuming that the mean IQ is 100, the standard deviation is 15, and the distribution of IQ scores is normal, what proportion of the population would score higher than Bob? Lower than Bob?
December 9, 2012 by Maurice

statistic
A grain mill manufactures 100-pound bags of flour for sale in restaurant supply warehouses. Historically, the weights of bags of flour manufactured at the mill were normally distributed with a mean of 100 pounds and a standard deviation of 15 pounds. a. What is the probability...
December 6, 2012 by anonymous

Statistics 2
The body temperature of healthy human beings can be assumed to have a normal distribution with mean  and standard deviation . Body temperature measurements taken from a sample of 130 healthy individuals shows the sample mean temperature to be 98.249O F and ...
December 16, 2013 by Steven

Statistics
In Professor White’s statistics course the correlation between the students’ total scores before the final examination and their final examination scores is r = 0.9. The pre-exam totals for all students in the course have mean 275 and standard deviation 50. The final exam ...
October 21, 2012 by Kevin

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