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February 6, 2016

Search: Standard Deviation-What?

Number of results: 9,259

statistics
A food snack manu. samples 15 bags of pretzels off the assembly line and weighed their contents. If the sample mean is 10.0 and the sample standard deviation is .15, find the 95% confidence interval estimate for the true mean.
January 3, 2013 by Kelly

Analytical Chemistry
The question: The pH of a solution is defined as pH = -log[H3O+]. If the pH of a solution is 3.72(+/- 0.03), what is the [H3O+] and its absolute standard deviation? Answer: How would I carry this out? I know to find the hydronium concentration wouldn't i just take e^3.72? How ...
January 28, 2013 by James

Statistics for Development
one hundred students seat for a mathematics examination.the scores from this examination are normaly distributed with a population mean of 65% and a standard deviation of (a=10).what is the probability that students score;(i)less than 75% (ii)at least85% (iii)between 60% and 75%
April 16, 2013 by Benson

statistics
The lifetime of a 2-volt non-rechargeable battery in constant use has a normal distribution with a mean of 516 hours and a standard deviation of 20 hours. Ninety percent of all batteries have a lifetime less than
May 31, 2013 by Anonymous

math 115
Let x be a continuous random variable that follows a normal distribution with a mean of 200 and a standard deviation 25. Find the value of x so that the area under the normal curve between and x is approximately 0.4798 and the value of x is greater than .
November 19, 2013 by louise

Statistics
Hello, my problem is I have a random sample of only 15 sales average is $115 with a known population standard deviation of $25.00. Obtain a 92% confidence interval and explain what your answer means. I am not sure what to do because the sample size is only 15. Thanks for your ...
November 29, 2013 by kim

statistics
The true highway mileage, Y, of a specific brand of hybrid vehicle has a normal distribution with a mean of 42 and a standard deviation of 1.5. Find the probability that a randomly selected hybrid vehicle gets more than 38 miles to the gallon.
June 17, 2014 by lisa

stats
Commuters were asked how many times a week they stop for coffee on their way to work. A survey found a mean of 3 times a week with a standard deviation of 0.55. Find the probability that the sum of 100 values is more than 290.
July 10, 2014 by brewster

math
Commuters were asked how many times a week they stop for coffee on their way to work. A survey found a mean of 3 times a week with a standard deviation of 0.55. Find the probability that the sum of 100 values is more than 290.
July 12, 2014 by brewser

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
October 1, 2014 by Anonymous

Statistics
Assume that the mean hourly cost to operate a commercial airplane follows the normal distribution with a mean of $2,325 per hour and a standard deviation of $240. What is the operating cost for the lowest 5 percent of the airplanes?
October 9, 2014 by Dany

7th grade math standard form scientific notation
In standard form: 5. 3.2 x 10^3 7. 4.1 x 10^8 9. Write the average weight of a blue whale, 2.6 x 10^5, in standard form. 15. 2.5 x 10^-3 17. 1.05 x 10^-2 19. Write the size of a grain of very fine sand, about 9.35 x 10^-3 cm, in standard form. Can somebody help? I have been ...
September 28, 2012 by Delilah

stat
the average number of pushups a United States Marine does daily is 300, with a standard deviation of 50. A random sample of 36 marines is selected. What is the probability that the sample mean is at most 320 push-ups? With a mean of 300, you are looking for a sample using a ...
April 15, 2007 by Anonymous

stats
A final exam in Math 160 has a mean of 73 with standard deviation 7.73. Assume that a random sample of 24 students is selected and the test score of the sample is computed. Assuming the scores are normally distributed, what percentage of sample means are less than 69?
January 23, 2012 by dan

Math (Algebra 1)
Consider the ages of 5 brothers: 32, 26, 28, 30, 28. Determine which of the following are true if a new brother is adopted at age 10. A) The median will decrease B) The mean will decrease C) The range will increase D) The standard deviation will decrease Please explain how you...
October 19, 2013 by Jordan

statistics
Answer the following. Show your work to get credit. Exam scores are normally distributed with a mean of 81 and a standard deviation of 9. a) What is the minimum score one must have to be in the top 4% of the students taking the exam? b) What percentage of scores are below 90? ...
October 13, 2014 by JAE

Statistics
In planning a family of 4 children assume boys and girls are equally likely on each birth. Find (i) the probability distribution (ii) the expected number of boys (iii) the standard deviation of the number of boys.
March 17, 2011 by Donald Crentsil

statistics
Assuming that the weights of newborn babies are normally distributed with mean 6.5 pounds and standard deviation 1.2 pounds, how many babies in a group of 80 do we expect to weigh more than 8.9 pounds? Please show work Thank you
June 28, 2011 by Harley

math
The diameter of an electric cable is normally distributed, with a mean of 0.8 inch and a standard deviation of 0.01 inch. What is the probability that the diameter will exceed 0.815 inch? (Give the answer to four decimal places.)
August 28, 2012 by Anonymous

math
The diameter of an electric cable is normally distributed, with a mean of 0.8 inch and a standard deviation of 0.01 inch. What is the probability that the diameter will exceed 0.815 inch? (Give the answer to four decimal places.) 1 0
August 29, 2012 by Anonymous

math help
A random sample of size 26 is to be selected from a population that has a mean = 46 and a standard deviation of 15. (f) What is the probability that the sample mean will be within 6 units of the mean? (Give your answer correct to four decimal places.)
June 16, 2013 by Sue 6f

Math Statistics
Answer the following. Show your work to get credit. Exam scores are normally distributed with a mean of 81 and a standard deviation of 9. a) What is the minimum score one must have to be in the top 4% of the students taking the exam? b) What percentage of scores are below 90? ...
October 13, 2014 by JAE

Statistics
What is the difference between normal distribution and approximate normally. Correct me if im wrong but I think the parameters of Normal is X~Normal (mu, standard deviation) but then approx. normal is X~Normal (mu, variation) im just really confused when you use each and such.
December 18, 2014 by Sarah

statistics
The weights of individual nails produced by the 'Hammer 'n Nail' hardware company follow a normal distribution with the average nail weight being 5.1 grams and the standard deviation in nail weight being 1.6 grams. When a nail is produced it is discarded if it weighs more than...
September 29, 2010 by GiNa

BCIT
A series of standard solutions of benzene in toluene solvent is to be prepared for an internal standard procedure with ethylbenzene serving as the internal standard. Tell how you would prepare the solutions, including the milliliters of benzene concentrations are to be 0.5%, 1...
November 10, 2013 by lori

Stats
A random sample obtained from a population has a mean of =100 and a standard deviation of = 20. The error between the sample mean and the population mean for a sample of n = 16 is 5 points and the error between a sample men and population mean for a sample of n = 100 is 2 ...
November 11, 2014 by Michelle

Stats
A random sample obtained from a population has a mean of =100 and a standard deviation of = 20. The error between the sample mean and the population mean for a sample of n = 16 is 5 points and the error between a sample men and population mean for a sample of n = 100 is 2 ...
March 13, 2015 by Mark

contemporary math
Intelligence quotients on the Stanford-Binet intelligence test are normally distributed with a mean of 100 and a standard deviation of 16. Use the 68-95-99.7 rule to find the percentage of people with the following IQs: a.) between 84 and 100 b.) below 52
June 23, 2008 by Alicia

Statistics
The Internal Revenue Service is studying contributions to charity. The mean calculated from a random sample of 36 returns is $150. Assume that the population standard deviation is known and equal to $20. Construct a 98 percent confidence interval for the population mean.
October 29, 2009 by Joshua

Stastics
Bank of Connecticut estimated that balance on credit cards have follows Normal Distribution mean $845 with standard deviation $270. Calculate probability that balance on a single credit card is greater than $750
March 7, 2010 by Mary

statistics
At a ski area in Vermont, the daytime high temperature is normally distributed during January, with a mean of 22F and a standard deviation of 10F. You are planning to snowboard there this January. What is the probability that you will encounter daytime highs of a) 42F or ...
April 23, 2010 by Rose

statistics
At a ski area in Vermont, the daytime high temperature is normally distributed during January, with a mean of 22F and a standard deviation of 10F. You are planning to snowboard there this January. What is the probability that you will encounter daytime highs of a) 42F or ...
April 29, 2010 by john

college
Suppose that, for a certain exam, a teacher grades on a curve. It is known that the grades follow a normal distribution with a mean of 70 and a standard deviation of 7. There are 45 students in the class. How many students should receive an A? Please, round your answer to the ...
December 22, 2010 by Anonymous

statistics
we are interested in testing at level of significance alpha =10 whether the population mean is different than 15. a random sample of size 25 is taken with a mean of 13.9. assume standard deviation is 2 and normally distributed population. find the values for zcrit
December 6, 2011 by jen

statistics
In a survey of 400 college students, 40 were left-handed. Treating the sample as if it were random and using 0.015 as the standard deviation of the sampling distribution of the sample proportion, what is the lower bound of a 95% confidence interval for the population proportion?
May 18, 2012 by D

statistics college
suppose we have a set of blood pressure set with a mean of 120 systolic and a sample standard deviation of 20 points assume a normal distribution of what two values should 95% of all systolic bp lie
May 22, 2012 by melba

Stat
The salaries at a corporation are normally distributed with an average salary of $29,000 and a standard deviation of $4,000. What is the probability that an employee will have a salary between $22,520 and $23,480? Enter your answer rounded to exactly 4 decimal places.
June 5, 2012 by Sam

statistics
A class test resulted in a mean score of 60% and a standard deviation of 15%. You scored 75%. Assuming the scores follow a normal distribution, and there are 200 in the class, how many students scored better than you? Give your answer to the nearest whole number.
August 30, 2012 by rebecca

statistics
The average homicide rate for the cities and towns in a state is 10 per 100,000 population with a standard deviation of 2. If the variable is normally distributed, what is the probability that a randomly selected town will have a homicide rate greater than 14?
March 24, 2013 by brittany

Statistics
A simple random sample of 10 households, the number of TV's that each household had is as follows: 1, 3, 1, 2, 0, 2, 1, 1, 1, 5 Assume that it is reasonable to believe that the population is approximately normal and the population standard deviation is 0.56. What is the lower ...
June 26, 2013 by Anonymous

Math/Statistics
A statistics teacher believes that the final exam grade for her elementary stats class have a normal distribution with a mean of 82 and a standard deviation on 8. Find the score which separates the top 10% of the scores from the lowest 90% of the scores.
August 11, 2013 by Sean

Statistics
The distribution of heights of women aged 20 to 29 is approximately normal with a mean of 2.8 inches and standard deviation of 2.8 inches. The height (+/- 0.1 inch) of the middle 99.7% falls between a low of ?? inches and a high of ?? inches. Please help on how I set this up ...
September 10, 2015 by Angel

Statistics
The grades in the final exam of a random sample of 25 students produce a standard deviation, s = 9.5. a) Construct a 90% confidence interval estimate for the population variance, . b) Can we infer at 10% level of significance that the population variance is significantly ...
November 25, 2014 by Kendra

College of education ekiadolor Benin
The scores of an achievement test given to 100,000 students are normally distributed with mean 500 and standard deviation 100.what should the score of a student be to place him or her among the 10% of the students?
June 14, 2015 by Biriemi powei

Stats
workers at a large toxic cleanup project are concerned that their white blood cell counts may have been reduced. The white blood cell count in the general population is known to have a mean of 7500 cells/mL with a standard deviation of 1750cells/mL a)what is the probability of...
May 23, 2015 by Ish

statistics
/3 points Notes Question: TanColM7 8.6.003. TKK Products manufactures electric light bulbs in the 50-, 60-, 75-, and 100-watt range. Laboratory tests show that the lives of these light bulbs are normally distributed with a mean of 774 hr and standard deviation of 68 hr. Find ...
October 15, 2010 by br0Ok3

statistics
given the group of numbers: 8,9,10,10,10,11,11,11,12,13. which of the following are the same? a)range and mean,b)mode and median, c)standard deviation and mode d)mean and median, e)none
April 22, 2011 by BV

Statistics
True or false? If the original x distribution has a relatively small standard deviation, the confidence interval for will be relatively short. Answer True False
July 7, 2012 by Desperate

Rioja
A normally distributed population with 200 elements has a mean of 60 and a standard deviation of 10. The probability that the mean of a sample of 25 elements taken from this population will be smaller than 56 is:
February 22, 2013 by Laws

statistics
A teacher finds that the test scores of a group of 40 students have a mean of 75 and a standard deviation of 10. If Anne has a test score of 88, what is Annes z-score?
November 14, 2013 by latisha

Probability/Statistics
Assume 20 oz. cola bottles are filled so that the mean amount of liquid contained in the bottle is 20 oz and the standard deviation is .12 oz. If a bottle is randomly selected, find the probability that the number of ounces in that bottle is greater than 20.21 oz.
June 21, 2008 by thomas

statistics
Bob is a salesman. He receives $20 for each sales plus a fixed salary of $100 per week. Bob's average weekly sales is 70 units with a standard deviation of 15. Bob works 45 weeks a year.
September 18, 2011 by tuyet

Statistics
If red has a probability of occurrence of .70 and black has a probability of occurrence of .30 and they are the only choices what is the probability that you pick the right color 10 out of 10 times and what is the standard deviation. I keep getting (.70*.50) + (.30*.50) = .50...
February 11, 2012 by Joe D.

statistics
Suppose the final exam scores in a large class is symmetric mound shaped with a mean of 70 points and standard deviation of 10 points. The percentage of students in the class who receive more than 60 points is approximately
February 17, 2012 by Anonymous

Math
An aptitude test has a mean of 300 and a standard deviation of 40. The test scores are normally distributed. If 1000 people take the test, find the number of people who will score between 280 and 360.
July 12, 2014 by Shelagh

Statistics
the age of costumers for a particular retail store follows a normal distribution with a mean of 37.5 years and a standard deviation of 7.6 years. what is the probability that the next costumer who enters the store will be less than 42 years old?
March 15, 2015 by Leo Elvis

Statistics
Assuming that the heights of college women are normally distributed with mean 62 inches and standard deviation 3.5 inches, what percentage of women are between 58.5 inches and 72.5 inches? (Points: 5) 34.1% 84.0% 15.7% 13.6% 97.6%
June 20, 2010 by alex

statistics
Heights of young adult US women are approximately normal with mean 64" and standard deviation 2.7". What proportion of all US young adult women are taller than 6 feet?
September 9, 2010 by Anonymous

Physics
Can someone please tell me how to calculate the standard deviation of the following values? 0.985 0.985 1.005 1.455 1.035 And please for the following numbers too 1.47 1.52 1.50 1.45 1.39
February 8, 2011 by Abi

math
i took the sat and recieved a score of 488 on the math section. the average score was 445 with a standard deviation of 110. where does my score fit in the sample and what is the z score?
July 29, 2011 by patricia

statistics
Heights of young adult U.S. women are approximately normal with mean 64" and standard deviation 2.7". What proportion of all U.S. young adult women are taller than 6 feet?
January 23, 2012 by Ashley

Statistics
The annual precipitation for one city is normally distributed with a mean of 72 inches and a standard deviation of 3.5 inches. In 95% of the years, the precipitation in this city is between___ and ___
July 23, 2012 by Marc

Math - Please help
The population standard deviation of people who shop online is 3.1. If you want to be 75% confident that the sample mean is within 10% of the population mean, how many people must be surveyed?
December 4, 2012 by Alley

algebra 2
The average score on a standardized test is 750 points with a standard deviation of 50 points. What is the probability that a student scores more than 700 on the standardized test?
September 23, 2014 by Anonymous

Statistics
A simple random sample of 60 items resulted in a sample mean of 64. The population standard deviation is 16. a. Compute the 95% confidence interval for the population mean (to 1 decimal).
October 28, 2014 by Anonymous

Statistics and probability
A psychologist tested the IQ in a sample of 36 children. Their mean IQ was 104. What is the probability of getting an IQ score of 104 or higher? The mean is 100, and the standard deviation is 15
November 8, 2015 by Echell

Quantitative Analysis
Under conditions where a large sample is used in experimental research, and "power" of a statistical test is maximized, it is possible to have statistically significant results, yet a fairly small...? A. Ethical concern B. Effect size C. Set of assumptions D. Standard Deviation
November 8, 2013 by Stacie

Salary Related - Stats question
The monthly starting salaries of students who receive engineering degrees have a standard deviation of $600. What sample size should be selected so that there is 0.95 probability of estimating the mean monthly income within $150 or less?
November 25, 2009 by Desire

Statistics
A bank wishes to estimate the mean balances owed by their MasterCard customers within $75. The population standard deviation is estimated to be $300. If a 98% confidence interval is used, how many cardholders should be sample. Please provide sample size formula in calcutions.
January 26, 2010 by Bryant

stats
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? A...
July 7, 2010 by Ali

Statistics
When fifteen vehicles were observed at random for their speeds (in M.P.H.) on a freeway, the following data were obtained. 61 53 57 55 62 58 60 54 62 60 59 66 55 54 63 Suppose that from past experience it may be assumed that vehicle speed is normally distributed with standard ...
April 29, 2012 by Jennifer

Statistics
When fifteen vehicles were observed at random for their speeds (in M.P.H.) on a freeway, the following data were obtained. 61 53 57 55 62 58 60 54 62 60 59 66 55 54 63 Suppose that from past experience it may be assumed that vehicle speed is normally distributed with standard ...
April 30, 2012 by Beth

statistics
a. Compute the mean, median, and mode. b. Compute the variance, standard deviation, range, coefficient of variation, and Z scores. Are there any outliers? Explain. c. Are the data skewed? If so, how? d. Based on the results of (a) through (c), what conclusions can you reach ...
December 23, 2012 by lou

Statistics
The mean monthly rent for a one-bedroom apartment without a doorman in Manhattan is $2,636. Assume the standard deviation is $500. A real estate firm samples 100 apartments. What is the probability that the average rent of the sample is more than $2,680?
June 20, 2013 by Anonymous

Math
assume that the speed of automobiles on an expressway during rush hour is normally distributed with a mean of 62 mph and standard deviation of 5 mph. What percent of cars are traveling faster than 62 mph? How would I work this problem out?? Thanks for any and all help anyone ...
February 20, 2010 by Bianca

Statistics
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 80 values is greater than 190.
May 11, 2015 by Jake

Math
The MPG for a certain compact car is normally distributed with a mean of 31 and a standard deviation of 0.8. what is the probability that the MPG for a randomly selected compact car would be less than 32?
March 25, 2009 by Nate

Statistics
Assuming that the heights of college women are normally distributed with mean 62 inches and standard deviation 3.5 inches, what percentage of women are between 58.5 inches and 72.5 inches? 34.1% 84.0% 15.7% my answer was 13.6 13.6% is this correct 97.6%
June 20, 2010 by Jack

Statistics
The weight of a product is normally distributed with a standard deviation of .8 ounces. What should the average weight be if the production manager wants no more than 5% of the products to weigh more than 5.3 ounces?
October 6, 2010 by Beverley

math
If you charge care for dogs 100 dollars plus an annual rate of 30. And cats 120 and an annual rate of 35 dollars, what is the difference of the standard deviation of the variables?
December 3, 2010 by jhenssine

Statistics
The null hypothesis,H0:u=48,was tested against the alternative hypothesis,H1:u>48.A sample of 75 resulted in a calculated p-value of 0.102.if standard deviation=3.5,the value of the sample mean is?need help
March 23, 2011 by Joel

stats
The weight of a product is normally distributed with a standard deviation of .8 ounces. What should the average weight be if the production manager wants no more than 1% of the products to weigh more than 7.3 ounces?
June 14, 2011 by jenny

statistics
The average score on a standardized test is 500 points with a standard deviation of 50 points. What is the probability that a student scores between 450 and 600 on the standardized test?
July 21, 2011 by tom

statistics
A normal distribution has a mean of = 100 with standard deviation = 20. If one score is randomly selected from this distribution, what is the probability that the score will have a value between X = 80 and X = 100?
March 7, 2012 by Asia

statistics
Given the length an athlete throws a hammer is a normal random variable with mean 50 feet and standard deviation 5 feet, what is the probability he throws it between 50 feet and 60 feet?
October 19, 2012 by Alex

Stats
students reported studying an average of 9.92 hours a week, with a standard deviation of 4.54. Treating this class as the population, what percent of students study more than 12 hours a week
December 16, 2012 by Anonymous

statistics
the probability that a football game will go into overtime is 17%. In 240 randomly selected football games, what is the mean and the standard deviation of the number that went into overtime
June 23, 2013 by erin

Stats
A random sample of size 100 is drawn from a population with a standard deviation of 10. If only 5% of the time a sample mean greater than 20 is obtained, the mean of the population is ______.
December 13, 2013 by Matthew

STATS
Suppose that the average weight of students in a statistics class is 75.5 kilograms with a standard deviation of 10.3 kilograms. Using the 68-95-99.7 rule, what is the lower bound for the weight of the top 2.5% of students?
February 11, 2014 by Tracy

Statistics
the average numbers of hours a cat sleep is approximately normally distributed with a mean of 15 hours and a standard deviation of 1.7 hours; what percentage of cats sleep between 13 and 18 hours
April 27, 2014 by Belinda

algebra 2
A newspaper claims that 52% of voters will vote for a particular candidate in an upcoming election. A random survey of 1000 voters shows that 48% will vote for that candidate, with a standard deviation of 3%.
August 1, 2014 by george

stats
The probability that a football game will go into overtime is 18%. In 140 randomly selected football games, what is the mean and the standard deviation of the number that went into overtime?
October 21, 2014 by bob

Algebra 1
A teacher graded the tests for each of her students. She calculated a mean grade of 80 and a standard deviation of 3. One of her students, Katrina, had a z-score of 2. What grade did Katrina get on the test?
May 10, 2015 by Jacob

math
Hi, How do I find the coefficient of variation? I found the sample variance and the standard deviation for the problem I'm trying to solve, but I can't find the coefficient of the variation
May 3, 2009 by Stella

math
Hi, How do I find the coefficient of variation? I found the sample variance and the standard deviation for the problem I'm trying to solve, but I can't find the coefficient of the variation
May 3, 2009 by Stella

statistics
Suppose a random sample of 36 is selected from a population with a standard deviation of 12. If the sample mean is 98, the 99% confidence interval to estimate the population mean is
April 25, 2011 by mona

statistics
If you have a population mean of 50 and a population standard deviation of 5 and you select a sample size of 100, what is the probability that the sample mean is between 47 and 49.5?
April 27, 2011 by tom

math
the rate of return for an investment can be described by a normal distribution with mean 22% and standard deviation 3%. what is the probability that the rate of return for the investment will be at least 15%?
April 27, 2011 by Carola

statistics
Bob scores 610 on his SAT's. If the mean score is 580 and the standard deviation is 115, what percentile is Bob's SAT score?
May 21, 2012 by jordan

stats
Joes test score was 450(1 standard deviation below the population mean550) A good guess for Joes test score is
February 8, 2015 by ben

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