Thursday

September 1, 2016
Number of results: 9,680

**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 deviation=...
*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*

**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 *

**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 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*

**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*

**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 25, 2011 by Max*

**statistics**

According to the local real estate board, the average number of days that homes stay on the market before selling is 78.4 with a standard deviation equal to 11 days. A prospective seller selected a random sample of 36 homes from the multiple listing service. Above what value ...
*July 6, 2013 by Anonymous*

**Statistics**

A survey of 250 lobster fisherman found that they catch an average of 32 pounds of lobster per day with a standard deviation of four pounds. If a random sample of 30 lobster fisherman is selected, what is the probability that their average catch is less than 31.5 pounds?
*May 7, 2014 by Mark*

**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*

**math**

In a time-use study, 20 randomly selected managers were found to spend a mean of 2.40 hours each day on paperwork. The standard deviation of the 20 scores is 1.30 hours. Also, the sample data appear to have a bell-shaped distribution. Construct the 95% confidence interval for ...
*July 29, 2012 by becky*

**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*

**statistics**

The owner of a computer repair shop has determined that their daily revenue has mean $7200 and standard deviation $1200. The daily revenue totals for the next 30 days will be monitored. What is the probability that the mean daily revenue for the next 30 days will exceed $7000?
*November 8, 2011 by UG*

**PROBABILITY**

The total amount being spent on personal calls in a month by employees of a company follows a normal distribution with a mean of $900 and a standard deviation of $50. Find the probability that in a randomly selected month the amount spent on personal calls is between $775.00 ...
*May 30, 2010 by BBABY*

**statistics**

The number of cars sold annually by used car salespeople is normally distributed with a standard deviation of 18. A random sample of 310 salespeople was taken and the mean number of cars sold annually was found to be 71. Find the 94% confidence interval estimate of the ...
*May 9, 2012 by lupita*

**statistics**

Sign in Assume that the mean score on a certain aptitude test across the nation is 100, and that the standard deviation is 20 points. Find the probability that the mean aptitude test score for a randomly selected group of 150 8th graders is between 99.5 and 100.5. Sign in
*May 20, 2012 by m elissa*

**stadistics**

If 200 of the adults surveyed were in the age category of 24 and under and they provided a standard deviation of $14.50, construct a 95% confidence interval for the weekly average expenditure on fast food for adults 24 years of age and under. Assume fast food weekly ...
*June 19, 2012 by victoria*

**statistics**

The duration of time it takes General Motors to build a car is normally distributed with a mean of 31 hours and a standard deviation of 2 hours. a) What is the probability that a single car, selected at random, will take between 28 and 34 hours? b) What is the probability that...
*April 25, 2013 by kevin*

**Math - Intro to Statistics (High School)**

The average square footage in an apartment in a town is 1,800 square feet with a standard deviation of 120 square feet. The square footage is normally distributed. You randomly select 10 apartments in the town. What is the probability that the mean will be more than 1900 ...
*April 30, 2013 by Group Stat Lab*

**Calculus**

Calculate μ and σ, where σ is the standard deviation, defined by the following. σ^2 = integral between (−∞,∞) (x-μ)^2 p(x) dx The smaller the value of σ the more tightly clustered are the values of the random variable X about the...
*November 22, 2015 by Anonymous*

**Calculus**

Calculate μ and σ, where σ is the standard deviation, defined by the following. σ^2 = integral between (−∞,∞) (x-μ)^2 p(x) dx The smaller the value of σ the more tightly clustered are the values of the random variable X about the...
*November 22, 2015 by Christina*

**stastics**

The value of “t” will increase as the standard deviation of the difference _____ and the difference between means ____. a. increase; decreases b. increases; increases c. decreases; decreases d. decreases; increases e. None of the above. Wouldn't this answer be either A or B ...
*April 25, 2016 by Lindsay*

**statistics**

a study of the time spent shopping in a supermarket for a market basket of 20 specific items showed an approximately uniform distribution between 20 minutes and 40 minutes. What is the probability that the shopping time will be a) between 25 and 30 minutes? b) less than 35 ...
*January 6, 2011 by ann*

**Statistics**

Ticket sales for opening night of a movie have a mean of $2100 with a standard deviation of $450. Assume these ticket sales follow a normal distribution. If a movie is selected randomly, what is the probability that opening night ticket sales are more than $1620?
*November 9, 2011 by Joe*

**statistics**

Consider a machine that fills soda bottles. The process has a mean of 15.9 ounces and a standard deviation of 0.06 ounces. The specification limits are set between 15.8 and 16.2 ounces. a)Compute and interpret the machine’s Cp b)Compute and interpret the machine Cpk c)What % ...
*December 2, 2012 by Paul*

**statistics**

a vending machine dispenses coffee into an 8 oz cup. the amount of coffee dispensed into the cup is normally distributed with a standard deviation of 0.03 oz.you can allow the cup to overfill 5 percent of the time. what amont should you set as the mean amount of coffee to be ...
*February 10, 2013 by stephanie*

**Math**

Actual lengths of pregnancy terms are nearly normally distributed about a mean pregnancy length (of about 38-39 weeks) with a standard deviation of 15 days: about what percentage of births would be expected to occur within 15 days of the mean pregnancy length?
*February 12, 2013 by Daniel*

**Help with Statistics (T-value and decision rule)**

For a random sample of 12 observations, the sample mean was 407 and the standard deviation was 6. Using the .05 significant level, answer the following questions. What would the t value be? What is the decision rule? **** I think the t-value would be t = -3.0845 Any help would...
*December 5, 2014 by Jennifer*

**statistics help**

Tests on a Chevy Cobalt incdicate a population mean of 32 mpg and a population standard deviation of 3.5 mpg. You take an SRS (sample random sample) of 10 cars to get a sample mean. What is the probability that your sample mean is greater than 34 mpg? I am not sure how to go ...
*December 8, 2015 by S*

**Stats**

A bottling company uses a filling machine to fill glass bottles with mango juice. The bottles are supposed to contain 300 milliliters (ml). In fact the amounts vary according to a normal distribution with mean = 298 and standard dev = 3 ml. What is the probability that an ...
*March 13, 2007 by LINDA*

**maths(Please help me out)**

A survey of mobile call interconnectivity indicates that the average time it takes to connect calls from one network to the other is 25 seconds.Assume the variable is approximately normally distributed and the standard deviation is 4.5 seconds.if 80 calls are randomly selected...
*May 4, 2016 by Ruby*

**Sampling Distribution**

It was reported by the National Forensic Center in the Guide to Experts Fees, 1998-99 that the average fee of forensic accountants for court testimony was 1500. Assume that the population standard deviation is 600. What is the probability that, in a random sample of 100 ...
*May 17, 2011 by Angela*

** Statistics**

A recent study of US children under 11 years old found that they spend on average 142 minutes a day watching tv. Assuming normal distribution with the standard deviation of 44 minutes, answer the following. A) what percent of children of this age spends over 90 minutes per day...
*November 30, 2014 by Junior*

**statistic**

The accounting department at Weston Materials, Inc., a national manufacturer of unattached garages, reports that it takes two construction workers a mean of 32 hours and a standard deviation of 2 hours to erect the Red barn model. Assume the assembley follow the normal ...
*July 28, 2008 by savon*

**Math Probability**

Super stumped... Help please. The average distance geese fly south in the winter is approximately 380 miles with a standard deviation of 60 miles. Assuming that the distances are normally distributed, find the probability that a randomly selected goose migrates a distance of: ...
*April 30, 2013 by Patricia Marzetta*

**statistics**

The population mean and standard deviation are given. Find the required probability and determine whether the given sample mean would be considered unusual. For a sample of n=36, find the probability of a sample mean being less than 12.2 if M=12 and O=0.95
*November 16, 2010 by Anonymous*

**intro to statistics**

a vending machine dispenses coffee into an 8 oz cup. the amount of coffee dispensed into the cup is normally distributed with a standard deviation of 0.03 oz.you can allow the cup to overfill 1 percent of the time. what among should you set as the mean amount of coffee to be ...
*October 29, 2008 by jennifer*

**STATS**

For Tommy Bench, a minor league pitcher, the times between pitches are normally distributed with a mean of 36 seconds and a standard deviation of 2.5 seconds. If Bench performs 50 pitches, how many of them (to the nearest whole number) do you expect to have times-between-...
*June 18, 2012 by Mickie*

**statistics**

You want to estimate the difference in grade point averages between two groups of university students to be accurate within 0.2 grade point, with probability approximately equal to 0.95. If the standard deviation of the grade point measurements is approximately equal to 0.6, ...
*August 13, 2014 by Bob*

**Statistics**

An economist found that a random sample of 42 high school teachers had an average annual salary of $56,490. A previous study showed that the population standard deviation is $4150. Find the 99% confidence interval for µ, the average annual salary of all high school teachers.
*December 17, 2012 by Alison*

** Math**

If light bulbs have lives that are normally distributed with a mean of 2500 hours and a standard deviation of 500 hours, use the 68-95-99.7 rule to approximate the percentage of light bulbs having a life between 2000 hours and 3500 hours? A. About 13.5% B. About 50% C. About ...
*May 4, 2016 by angela*

**Math ---HELP!!!!!**

light bulbs have lives that are normally distributed with a mean of 2500 hours and a standard deviation of 500 hours, use the 68-95-99.7 rule to approximate the percentage of light bulbs having a life between 2000 hours and 3500 hours? A. About 13.5% B. About 50% C. About 68...
*May 5, 2016 by angela*

**chemistry**

In choosing a primary standard we generally choose something that 1. All of these are properties we want in a primary standard. 2. has a low percent purity. 3. None of these are properties we want in a primary standard. 4. has several different possible reaction pathways. 5. ...
*September 19, 2012 by cheri*

**Math 156**

The systolic blood pressures of the patients at a hospital are normally distributed with a mean of 136 mm Hg and a standard deviation of 13.4 mm Hg. Find the two blood pressures having these properties: the mean is midway between them and 90% of all blood pressures are between...
*August 7, 2009 by Emory*

**statistics**

To see whether people are keeping their car tires inflated to the correct level of 35 pounds per square inch (psi), a tire company manager selects a sample of 36 tires and checks the pressure. The mean of the sample is 33.5 psi, and the population standard deviation is 3 psi. ...
*October 7, 2013 by Anonymous*

**college statistics **

the math SAT scores for all students who applied to the school of engineering are normally distributed with M=629 and standard deviation of 60. the school of engineering has decided to accept those students whose scores fall in the top 15%. what is th minimum score an appliant...
*November 6, 2014 by Chelsea *

**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 ¯ x will be ...
*August 9, 2010 by houston*

**Statistics**

A soft drink vending machine is supposed to fill cups with pop. The cups hold exactly 8 oz of liquid. Suppose the actual amount dispensed by the machine follows a normal distribution with mean 7 oz. If it is found that exactly 4 percent of the cups overflow, what is the ...
*September 24, 2007 by Lily*

**stats**

A soft drink vending machine is supposed to fill cups with pop. The cups hold exactly 8 oz of liquid. Suppose the actual amount dispensed by the machine follows a normal distribution with mean 7 oz. If it is found that exactly 4 percent of the cups overflow, what is the ...
*September 24, 2007 by Lily*

**statistics**

2. The director of admissions at a large university advises students that the cost of textbooks will average more than $300 for a typical semester. A random sample of 80 students enrolled in the university shows a sample mean cost of $315.40 and a sample standard deviation of...
*August 22, 2010 by Elizabeth*

**prob/stats**

Nationwide, the amount charged by doctors for performing a particular minor surgical procedure averages $1220 and varies with a standard deviation of $270. We randomly select 140 bills from the population of all bills charged for this surgery. Let represent the average amount ...
*March 29, 2011 by amanda*

**prob/stats**

Nationwide, the amount charged by doctors for performing a particular minor surgical procedure averages $1220 and varies with a standard deviation of $270. We randomly select 140 bills from the population of all bills charged for this surgery. Let represent the average amount ...
*March 29, 2011 by amanda*

**statistics**

a manufacturer of bicycle tire has developed a new system which he claims an average life span of 5 years. with the standard deviation of 1.2 years a dealer product claims that the average life span of 150 samples is only 3.5 years. test the difference of population and sample...
*October 2, 2012 by jericho*

**Statistics**

Suppose that the weight of male babies less than 2 months old is normally distributed with mean 11.5 pounds and standard deviation 2.7 pounds. A sample of 36 babies is selected. What is the probability that the average weight of the sample is less than 11.07 pounds? Write only...
*October 6, 2015 by Tommy*

**statistics**

The time needed to complete a final examination in a particular college course is normally distributed with a mean of 79 minutes and a standard deviation of 8 minutes. Answer the following questions. Assume that the class has 60 students and that the examination period is 90 ...
*November 15, 2015 by margaret*

**Statistics **

The Weight of a small Starbucks coffee is normally distributed random variable with a mean of 360 grams and a standard deviation of 9 grams. Find the weight that corresponds to each event. a. highest 10% b. highest 50% c. highest 5% D. highest 80% e. lowest 10% f. middle 50% g...
*April 11, 2014 by Kelly*

**Math**

In the average ball game, the sum of the scores of both teams is 4545, with a standard deviation of 55. If the score of a game resulted in a z-score of 1.801.80 and the winning team had a score of 3333, what was the other team's score?
*July 19, 2015 by Peewee*

**statistic**

the mean of adult men is 172 pounds with a standard deviation of 29 pounds. ask 20 men thier weight and use excel to calculate the mean. test the hypothesis that the mean is not 172 pounds at the .10 significance level. and how many men should be sampled if you want to be 98% ...
*December 4, 2010 by natasha*

**physics**

A cart of mass m = 0.84 kg on a track undergoes a collision with another cart. It's velocity before and after the collision, vi and vf is measured and found to be vi = 1.32±0.04 m/s and vf = 0.30±0.04 m/s. If the collision lasts a time interval Δt = 0.100±0.006 s, ...
*February 17, 2011 by charisse*

**physics**

A cart of mass m = 0.84 kg on a track undergoes a collision with another cart. It's velocity before and after the collision, vi and vf is measured and found to be vi = 1.32±0.04 m/s and vf = 0.30±0.04 m/s. If the collision lasts a time interval Δt = 0.100±0.006 s, ...
*February 17, 2011 by charisse*

**Statistics/Probability**

A component is rejected if its has a diameter less than 70mm, reworked if the diameter is between 70 and 73.5mm or more than 78.5mm. The diameter of a component is normally distributed with a mean 76mm and standard deviation 2.5mm. In a batch of 400 components, determine the ...
*July 20, 2014 by Koylar*

**AP Statistics**

Do the samples appear to be from the same population? Why or why not? Support your answer with numerical facts and convincing reasons and explanations Chemical distribution stats: Five # summary: (2.29816, 2.29869, 2.299152, 2.30074) Mean: 2.299706 Standard deviation: 0....
*October 7, 2015 by Ashley*

**math - Please help me to understand**

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.) I don't ...
*November 28, 2011 by Jennifer*

**math - Please help me to understand**

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.) I don't ...
*November 29, 2011 by Jennifer*

**math (stats)**

The cholesterol levels of adult American women are approximately normal with the mean of 188 mg/dl and a standard deviation of 24 mg/dl. a company wants to test a certain medication for women falling in the highest 15% of cholesterol readings. what is the lowest cholesterol ...
*November 17, 2014 by jeff*

**Statistics**

A sociologist interested in cultural differences compared women of two ethinic groups on a Role Approval Index (high scores mean high degrees of approval of one's social role). The results are as follows: Ethnic Group A: N = 15 M= 55 S2 = 6.5 Ethnic Group B : N = 23 M= 51 S2...
*October 11, 2009 by Trey*

**Statistics**

A sociologist interested in cultural differences compared women of two ethinic groups on a Role Approval Index (high scores mean high degrees of approval of one's social role). The results are as follows: Ethnic Group A: N = 15 M= 55 S2 = 6.5 Ethnic Group B : N = 23 M= 51 S2...
*October 16, 2009 by Ken*

**statistics**

6. A sociologist interested in cultural differences compared women of two ethinic groups on a Role Approval Index (high scores mean high degrees of approval of one's social role). The results are as follows: Ethnic Group A: N = 15 M= 55 S2 = 6.5 Ethnic Group B : N = 23 M= 51 ...
*May 2, 2010 by Anonymous*

**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*

**Business Analytics statistics**

I dont under stand ho to get the answer to this excel question can anyone help? and email me back skylerbloo at netscape . net The assignment is in three parts: 1. An analytic section that you will submit as an Excel spread sheet 2. A PowerPoint presentation of 3 to 5 slides. ...
*August 19, 2009 by Trisha*

**Statistics**

Are these statements true or false? 1. The sample mean, the sample proportion and the sample standard deviation are all unbiased estimators of the corresponding population parameters. 2. If the population is normally distributed with known variance then the sample mean may not...
*November 5, 2010 by help*

**Stats**

You will need to examine two of the nine sections of data: one section of qualitative data (choose either Gender or Position) one section of quantitative data (choose either Intrinsic or Extrinsic) Each section should include all data points listed in the column for the ...
*November 10, 2011 by Puppygirl*

**stats**

In a transportation study of 20 large cities, it was found that the mean of the number of cars per person was 0.504. (Some of the people in the city are children.) The study also stated that the standard deviation s was 0.123. Find a 95 % confidence interval for the true mean ...
*March 31, 2013 by chris*

**stats**

n a transportation study of 20 large cities, it was found that the mean of the number of cars per person was 0.504. (Some of the people in the city are children.) The study also stated that the standard deviation s was 0.123. Find a 95 % confidence interval for the true mean ...
*March 31, 2013 by chris*

**math foundations 20**

How do I solve normal distribution word problems? Ex A manufacturer offers a warranty on it's coffee makers. The coffee makers have mean lifespan of 4.5 years, with standard deviation of 0.7 yeaes. For how long should the coffee makers be covered by the warranty, if the ...
*June 9, 2014 by Ayane*

**Math ---HELP!!!!!**

A researcher wishes to estimate the mean amount of money spent per month on food by households in a certain neighborhood. She desires a margin of error of $30. Past studies suggest that a population standard deviation of $248 is reasonable. Estimate the minimum sample size ...
*May 30, 2016 by angela*

**Statistics**

The fracture strength of a certain type of manufactured glass is normally distributed with a mean of 579 MPa with a standard deviation of 14 MPa. (a) What is the probability that a randomly chosen sample of glass will break at less than 579 MPa? (b) More than 590 MPa? (c) Less...
*January 8, 2012 by Mary Ann*

**statistics**

1. The fracture strength of a certain type of manufactured glass is normally distributed with a mean of 579 MPa with a standard deviation of 14 MPa. (a) What is the probability that a randomly chosen sample of glass will break at less than 579 MPa? (b) More than 590 MPa? (c) ...
*March 26, 2012 by Anonymous*

**Finance**

Niles is making an investment with an expected return of 12 percent. If the standard deviation of the return is 4.5 percent, and if Niles is investing $100,000, then what dollar amount is Niles 90 percent sure that he will have at the end of the year? A) $100,000.00 B) $104,...
*October 24, 2011 by James*

**statistics**

The distribution of weekly salaries at a large company is right skewed with a mean of $1000 and a standard deviation of $350. What is the probability that the sampling error made in estimating the mean weekly salary for all employees of the company by the mean of a random ...
*June 18, 2013 by Anonymous*

**probability**

Assume that head sizes (circumference) of new recruits in the Canadian armed forces can be approximated by a normal distribution with a mean of 22.8 inches and a standard deviation of 1.1 inches. (a)What proportion of recruits have head sizes between 22 and 23 inches? (b)Five ...
*November 3, 2014 by ashley*

**Statistics**

The distribution of weekly salaries at a large company is reverse J-shaped with a mean of $1000 and a standard deviation of $370. What is the probability that the sampling error made in estimating the mean weekly salary for all employees of the company by the mean of a random ...
*April 13, 2015 by Janet*

**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 (a) What is the probability that the average of this sample will be above 68.3 degrees F? Probability = (4 decimal places) (b) ...
*February 25, 2011 by Anna*