Thursday

September 3, 2015
Number of results: 8,904

**Statistics**

A quality control engineer is interested in the mean length of sheet insulation being cut automatically by machine. The desired length of the insulation is 12 ft. It is known that the standard deviation in the cutting length is 0.15 ft. A sample of 70 ut sheets yields a mean ...
*August 10, 2008 by Student*

**physics**

If the strip is 28 mm long, how far is the maximum deviation of the strip from the straight orientation? (The deviation is measured from the straight orientation from the interface of the two strips.) Radius of curvature is 53.7
*April 6, 2012 by Anonymous*

**physics**

If the strip is 29 mm long, how far is the maximum deviation of the strip from the straight orientation? (The deviation is measured from the straight orientation from the interface of the two strips.)Radius of curvature is 53.7 m
*April 7, 2012 by Anonymous*

**physics**

If the strip is 29 mm long, how far is the maximum deviation of the strip from the straight orientation? (The deviation is measured from the straight orientation from the interface of the two strips.)Radius of curvature is 53.7 m
*April 8, 2012 by Anonymous*

**Statistics**

I can do problems like this if the mean and standard deviation was given but what do I do if it's like this When asked whether they drink alcohol or not, 79 out of 441 college students said that they did not. Construct a 90% CI for the proportion of all college students that ...
*May 6, 2010 by John*

**AP Statistics**

Suppose a Normal model describes the fuel efficiency of cars currently registered on your state. The mean is 24 mpg, with a standard deviation of 6 mpg. -Describe the fuel efficiency of the worst 20% of all cars. I know that you convert 20% into decimal form to get .2 and put ...
*November 9, 2007 by Courtney*

**Statistics/Probability**

Each day a bakery delivers the same number of loaves of bread to local shop on the corner. On average the shop sells 75% of loaves. Assuming that the number of loaves sold per day has binomial distribution with a standard deviation of 9. Find the number of loaves the shop ...
*July 17, 2014 by Koylar*

**statistics**

interested in the mean IQ score of a given group of children. It is known that the IQ scores of the group have a standard deviation of . The psychologist randomly selects children from this group and finds that their mean IQ score is . Based on this sample, find a confidence ...
*December 21, 2014 by Anonymous*

**Stats**

The Ledd Pipe Company has received a large shipment of pipes, and a quality control inspector wishes to estimate the average diameter of these pipes. A random sample of 18 pipes produces an average diameter of 2.56 mm with a standard deviation of 0.05 mm. You may assume that ...
*November 28, 2012 by Matt*

**Statistics**

The standard deviation for a population is σ = 15.3. A sample of 36 observations selected from this population gave a mean equal to 74.8. a) Make a 90% confidence interval for μ b) Construct a 95% confidence interval for μ. c) Determine a 99% confidence interval...
*November 21, 2013 by ----*

**statistics**

Suppose a brewery has a filling machine that fills 12 ounce bottles of beer. It is known that the amount of beer poured by this filling machine follows a normal distribution with a mean of 12.44 ounces and a standard deviation of 0.06 ounce. Find the probability that a sample ...
*November 6, 2011 by Anonymous*

**statistics**

A sample of 352 subscribers to Wired magazine shows the mean time spent using the Internet is 13.4 hours per week, with a sample standard deviation of 6.8 hours. Find the 95 percent confidence interval for the mean time Wired subscribers spend on the Internet.
*March 19, 2012 by Annette*

**stats**

1)Suppose that the weight of tomato juice in mechanically filled cans follows a normal distribution with a mean of 464 grams and a standard deviation of 8 grams. a)A random sample of size n = 18 cans is taken. Will the sampling distribution of the sample mean weight be normal...
*June 28, 2015 by Liz*

**chemistry**

Why is the standard reduction potential E, for the standard hydrogen electrode 0.00V? Please help me explain the reason why to this problem
*May 22, 2008 by jennifer*

**chemistry**

Why is the standard reduction potential E, for the standard hydrogen electrode 0.00V? Please help me explain the reason why to this problem
*May 22, 2008 by kristine*

**Chemistry**

In a standard hydrogen electrode, why does increasing the partial pressure of H2 gas reduce the standard potential (E) of the cell?
*April 5, 2011 by John*

**Chemistry**

How do I find the pH of pure neutral H2O at o degrees celsius by using standard enthalpies and standard entropies
*April 21, 2011 by Tanya *

**statistics**

A sample of 100 patients who use the drug are followed over time. Those that use the drug have a mean life expectancy of 71.30 years. The mean life expectancy for the general population is 75.62 years. The population standard deviation is 28.
*September 20, 2014 by Michelle*

**statistics**

Ala rge fleet of cars is maintained with an average of 26 mpg. 50 recent trips displayed a mean of 25.02 mpg and standard deviation of 4.1 mpg. At the 5% level of significance, is their evidence the company has failed to keep their fuel goals? I did the math and got .03380315...
*November 30, 2013 by kim*

**Statistics**

A purchasing agent at the Kelly Bread Company wants to estimate the mean daily usage of rye flour. She takes a sample for 50 straight days and finds that the sample mean is 180 pounds with a sample standard deviation of 38.5 pounds. a) State the 90% confidence interval for the...
*April 16, 2013 by Jamie*

**statistics**

Membership in Mensa requires an IQ score above 131.5. Nine candidates take an IQ test and their summary scores indicate that their mean IQ score is 133. IQ scores are normally distributed and have a mean of 100 and a standard deviation of 15. If nine people are randomly ...
*November 6, 2014 by Ms.L*

**Statistic **

A random sample has 61 values. The sample mean is 9.9 and the sample standard deviation is 2. Use a level of significance of a=0.01 to conduct a right-tailed test of the claim that the population mean is 9.2 ( i.e, H_0: u= 9.2, H_1: u>9.2). A)Compute the sample test ...
*December 4, 2014 by Yira f *

**Statistics**

A sample of 64 observations is selected from a normal population. the sample mean is 215 and the standard deviation is 15. conduct the following test of hypothosis using the .3 significance level. Ho:u > or = 220 H1: u < 220 a) Is this a 1 tailed or 2 tailed test? b) ...
*October 3, 2008 by Shawn*

**statistics**

The numbers of hours of life of a torch battery is normally distributed with a mean of 150 hours and standard deviation of 12 hours. In a quality control test, two batteries are chosen at random from a batch. If both batteries have a life less than 120 hours, the batch is ...
*January 26, 2011 by Anonymous*

**math**

Assume that the average annual salary for a worker in the United States is $32,000 and that the annual salaries for Americans are normally distributed with a standard deviation equal to $7,000. Find the following: (A) What percentage of Americans earn below $24,000? (B) What ...
*July 19, 2012 by Rashonda*

**Math **

Can anyone help me with this question. What's the best answer? Choose from these answers: [(A):variance] [(B):standard deviation] [(C):sample mean] [(D):s-squared] [(E):unbiased estimate] 1.subtract the mean of all the scores from each score, then square that number and get ...
*April 24, 2015 by Anonymous*

**statistics**

for a particular sample of 77 scores on a psychology exam, the following results were obtained: first quartile=44, third quartile= 71, standard deviation=6, range=45, mean=64,median=57, mode=32, midrange=60 a)according to chevyshev's theorem how many students scored between 48...
*October 17, 2010 by mary- please show correct calculations*

**math please help**

Suppose that ice cream consumption per person at parties is normally distributed with a mean of 0.39 gallons, and a standard deviation of 0.26 gallons. If you are throwing a party with 33 guests, how much ice cream do you need to buy to make sure that the probability of having...
*October 24, 2014 by tommy*

**math**

A sample of 64 statistics students at a small college had a mean mathematics ACT score of 28 with a standard deviation of 4. Estimate the mean mathematics ACT score for all statistics students at this college. Give the 95% confidence interval.
*May 6, 2012 by jennifer*

**Math**

A sample of 64 statistics students at a small college had a mean mathematics ACT score of 28 with a standard deviation of 4. Estimate the mean mathematics ACT score for all statistics students at this college. Give the 95% confidence interval.
*June 21, 2012 by Jameson*

**Math**

A sample of 64 statistics students at a small college had a mean mathematics ACT score of 28 with a standard deviation of 4. Estimate the mean mathematics ACT score for all statistics students at this college. Give the 95% confidence interval.
*June 21, 2012 by Jameson*

**Statistics**

The populaion mean annual salary of service desk managers is $48,000 with a standard deviation of $1,800. A sample of 36 service desk managers is randomly selected. What is the probability the mean annual salary of the sample is less then $47,550?
*November 14, 2012 by Dorothy*

**math**

A sample of 64 statistics students at a small college had a mean mathematics ACT score of 28 with standard deviation of 4. Estimate the mean mathematics ACT score for all statistics students at college. Give the 95% confidence interval.
*June 5, 2014 by Erma*

**Elementary statistics **

Nine apples, four of which are rotten, are in a refrigerator. Three apples are randomly selected without replacement. Let the random variable x represent the number chosen that are rotten. Construct a table describing the probability distribution, then find the mean and ...
*February 29, 2012 by Rose Bud*

**Statistics Question (Confidence Interval)**

A sample of 15 recent college graduates found that starting salaries for attorneys in New York City had a mean of $102,342 and a standard deviation of $21,756. Construct a 95% confidence interval for the average starting salary of all attorneys in the city. A. (89869.82, ...
*March 14, 2012 by Mark*

**Stats Repost**

Your mathematics instructor claims that, over the years, 88% of his students have said that math is their favorite subject. In this year's class, however, only 21 out of 32 students named math as their favorite class. The teacher decides to conduct a test of the hypothesis H0...
*December 17, 2012 by Oops*

**math**

a potato chip manufacturer has been accused of shortchanging their customers with 10 ouce of bags potato chips. a sample of 50 of that company's 10 ounce bags was take, and it was found that the average weight was 9.8 ounces with a standard deviation of 0.3 ounces.can we ...
*April 25, 2013 by kiki*

**elizabeth high school**

. An admissions director wants to estimate the mean age of all students enrolled at a college. The estimate must be within one year of the population mean. Assume the population of ages is normally distributed. Determine the minimum required sample size to construct a 90% ...
*November 18, 2010 by minhaj*

**Statistics**

"Working Moms Journal" reported that the mean time a mother, with her small children, spends in at the convenience store is 7.3 minutes. A sample of 20 moms is chosen from your neighborhood, and it is found that the mean time they spend in a convenience store was 8.2 minutes ...
*March 10, 2013 by Nadine*

**math**

let the random variable x denote the number of girls in a five-child family. if the probability of a female birth is .5 find the probability of 0,1,2,3,4, and 5 girls in a five-child family. construct the binomial distribution and draw the histogram associated with the ...
*April 23, 2009 by miranda*

**Statistics**

Assume the body temperatures of healthy adults are normally distributed with a mean of 98.20 F and a standard deviation of 0.62 F (based on data from the University of Maryland researchers). a. If you have a body temperature of 99.00 F, what is your percentile score? b. ...
*April 19, 2010 by Sasha*

**statistics**

Assume the body temperatures of healthy adults are normally distributed with a mean of 98.20 F and a standard deviation of 0.62 F (based on data from the University of Maryland researchers). a. If you have a body temperature of 99.00 F, what is your percentile score? b. ...
*August 16, 2010 by sweet*

**statitics**

Assume the body temperatures of healthy adults are normally distributed with a mean of 98.20 F and a standard deviation of 0.62 F (based on data from the University of Maryland researchers). a. If you have a body temperature of 99.00 F, what is your percentile score? b. ...
*August 20, 2011 by ann*

**Math**

The diameters of grapefruits in a certain orchard are normally distributed with a mean of 5.52 inches and a standard deviation of 0.46 inches (A) What percentage of the grapefruits in this orchard is larger than 5.45 inches? (B) A random sample of 100 grapefruits is gathered ...
*October 28, 2012 by Michael*

**stats**

SAT math scores approx. follow a normal distribution, with mean 500 and standard deviation 100. What % of students should have an SAT math score above 500? I think I use mean (500) + z-score * SD (100), but I do not know how to get the z-score?
*September 28, 2009 by CM*

**statistics**

The number of pizzas consumed per month by university students is normally distributed with a mean of 9 and a standard deviation of 5. What is the probability that in a random sample of size 10, a total of more than 80 pizzas are consumed? (Hint: What is the mean number of ...
*March 25, 2012 by Lucy*

**Statistics**

A student wants to test her hypothesis she gives each of her students an IO test. She finds that the average IQ score is 115 and the standard deviation for the class is 30. There are 22 students in the class. She also knows that the population average IQ is 100 points. Ho:p=...
*May 5, 2014 by Keisha*

**stat**

the number of mosquitoes that brown bats can eat in an hour has a mean of 600 and a standard deviation of 200. a study observed a random sample of 80 little brown bats. hat is the minimum no. of mosquitoes that the upper 25% of little brown bats eat in an hour? Please.. I need...
*January 17, 2012 by Jeanie*

**statistics**

The distribution of the heights of men in the U.S. is normally distributed with a mean of 70 inches and a standard deviation of 5 inches. a) What is the probability of an american male being less than 60 inches tall? b) What is the probability of an american male being between...
*March 1, 2011 by Maddie Liguori*

**PSY315**

Based on the information given for each of the following studies, decide whether to reject the null hypothesis. For each, give (a) the Z-score cutoff (or cutoffs) on the comparison distribution at which the null hypothesis should be rejected,(b) the Z score on the comparison ...
*April 14, 2012 by Ashley*

**maths**

A statistician wants to estimate the mean weekly family expenditure on clothes. He believes that the standard deviation of the weekly expenditure is $125. Determine with 99% confidence the number of families that must be sampled to estimate the mean weekly family expenditure ...
*January 16, 2013 by sarah*

**Statistics Math**

The annual per capita consumption of fresh apples (in pounds) in a nearby state can be approximated by a normal distribution, with a mean of 15.4 pounds and a standard deviation of 3.8 pounds. (a) What is the smallest annual per capita consumption of apples that can be in the ...
*April 1, 2013 by TJ*

**Statistics**

In 2002, the average price of new homes in a certain suburb was $145,000. Assume that this mean is based on a random sample of 1000 new home sales and that the sample standard deviation is $24,000. Construct a 95% confidence interval for the 2002 mean price of all such homes
*May 11, 2012 by Nesa*

**statistic**

Suppose a 95% confidence interval for the mean salary of college graduates in a town in Mississippi is given by [$36,080, $43,920]. The population standard deviation used for the analysis is known to be $12,000. a. What is the point estimator of the mean salary of all college ...
*April 12, 2015 by Heather*

**intro to statistics**

"Working Moms Journal" reported that the mean time a mother, with her small children, spends in at the convenience store is 7.3 minutes. A sample of 20 moms is chosen from your neighborhood, and it is found that the mean time they spend in a convenience store was 8.2 minutes ...
*December 8, 2011 by Mark Jessen*

**statistics**

I am having trouble figuring out how to do this type of problem. Here is the current problem I am working on: the probability that a tomato seed will germinate is 60%. A gardener plants in batches of 12. A.) what is the probaility that exactly 10 seeds will germinate? B.) what...
*January 2, 2010 by Pam*

**Help Math!**

Battery Power Problem. 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 15hours. What proportion of these batteries can be expected to have lives of 322 hours or less? Assume a normal ...
*May 19, 2010 by Mariah*

**statistics**

An economist wants to estimate the mean income for the first year of work for college graduates who majored in biology. How many such incomes must be found if the economist wants to be 95% confident that the sample mean is within $500 of the true population mean? Assume that ...
*April 14, 2013 by Panther*

**statistics**

Use the given information to find the minimum sample size required to estimate an unknown population mean u. How many adults must be randomly selected to estimate the mean FICO (credit rating)score of working adults in a country? We want 95% confidence that the sample mean is ...
*November 15, 2013 by anonymous*

**Industrial Psychological Research**

what is the proportion of students with a raw score less than 10? if information was collected from fellow students the rating on a 5 point scale on 5 different questions. given a normally distributed population with a mean of 13, a standard deviation of 3, and 50 as the ...
*September 23, 2014 by Precious*

**statistics**

A 4 to 7 month old baby sleeps an average of 14 hours per day. At this age, babies sleep patterns follow normal distribution with the standard deviation of 1.6 a) is it unusual for a baby to sleep under 12 hours aday? b) In a random sample of 10 babies of this age,find the ...
*November 30, 2014 by adriana*

**STATISTICS**

It is generally believed that electrical problems affect about 14% of new cars. An automobile mechanic conducts diagnostic tests on 128 new cars on the lot. a. Describe the sampling distribution for sample proportion by naming the model and telling its mean and standard ...
*October 30, 2007 by LT*

**STATS**

Given a sample size of 18, with sample mean 660.3 and sample standard deviation 95.9 we are to perform the following hypothesis test. Null Hypothesis H0: = 700 Alternative Hypothesis H0: 700 At significance level 0.05 1. What is the critical value for this test? ...
*March 30, 2010 by Mary*

**AP Stats**

The distribution of heights of adult American men is approximately normal with mean 69 inches and standard deviation 2.5 inches. Use the 68-95-99.7 rule to answer the following questions: (d) A height of 71.5 inches corresponds to what percentile of adult male American heights...
*September 14, 2010 by Emily*

**Satistics**

A company that produces detergents wants to estimate the mean amount of detergent in 64-ounce jugs at a 99% confidence level. The company knows that the standard deviation of the amounts of detergent in all such jugs is .20 ounce. How large a sample should the company select ...
*November 21, 2013 by ----*

**chemistry**

What are standard temperature and pressure? Why was a standard needed?
*October 2, 2013 by Joseph*

**Math Help and check**

The weights of ripe watermelons grown at Mr. Smith's farm are normally distributed with a standard deviation of 2 lb. Find the mean weight of Mr. Smith's ripe watermelons if only 5% weigh less than 18 lb. (Give your answer correct to one decimal place.) Incorrect: Your answer ...
*June 15, 2013 by Tom 6*

**MATH,statistics**

At a recent scotch-tasting party, 20 faculty members and their (opposite sex) spouses were guzzling it back pretty well. One person quite correctly noticed that the women seemed to be drinking more than the men. If the mean number of drinks had by the men was 5, and that for ...
*November 2, 2012 by Tanya*

**Chemistry**

If calcium carbide has a standard enthalpy of formation of -59.8 kJ/mol and acetylene has a standard enthalpy of formation of 226.73 kJ/mol, what is the standard enthalpy change for the reaction?
*February 20, 2013 by Kelly*

**math**

A fitness company surveyed the weights of its 90 costumers. Assume that the weights are normally distrubted with a mean of 162 lbs and a standard deviation of 3.5 lbs. If you select one of its costumers randomly, what is the probability that the costumer's weight is a) more ...
*November 14, 2008 by devon*

**math**

A fitness company surveyed the weights of its 90 costumers. Assume that the weights are normally distrubted with a mean of 162 lbs and a standard deviation of 3.5 lbs. If you select one of its costumers randomly, what is the probability that the costumer's weight is a) more ...
*November 14, 2008 by devon*

**Chemistry Equilibrium**

Which of the following conditions is always true at equilibrium? deltaG=0, Q=1, K=1, deltaG=deltaG(standard), deltaG(standard)=0, Q=0, deltaG(standard)=1 I'm so confused, please help!
*March 14, 2013 by Student*

**12th grade**

2. Assume the body temperatures of healthy adults are normally distributed with a mean of 98.20 F and a standard deviation of 0.62 F (based on data from the University of Maryland researchers). a. If you have a body temperature of 99.00 F, what is your percentile score? b. ...
*June 15, 2010 by Anonymous*

**statistics**

The diameters of apples in a certain orchard are normally distributed with a mean of 4.77 inches and a standard deviation of 0.43 inches. Show all work. (A) What percentage of the apples in this orchard is larger than 4.71 inches? (B) A random sample of 100 apples is gathered ...
*November 2, 2010 by Valerie*

**statistics**

Employees in a large computer firm claim that the mean salary of the firms programmers is less than that of its competitors. The competitors salary is $47,000. A random sample of 30 of the firms programmers has a mean salary of $46,500 with a standard deviation of 5500. ...
*June 6, 2011 by Eric*

**Statistics**

Employees in a large computer firm claim that the mean salary of the firms programmers is less than that of its competitors. The competitors salary is $47,000. A random sample of 30 of the firms programmers has a mean salary of $46,500 with a standard deviation of 5500. ...
*June 7, 2011 by Kelly*

**statistics**

Employees in a large computer firm claim that the mean salary of the firms programmers is less than that of its competitors. The competitors salary is $47,000. A random sample of 30 of the firms programmers has a mean salary of $46,500 with a standard deviation of 5500. ...
*June 14, 2011 by Shawnie*

**statistics**

The diameters of apples in a certain orchard are normally distributed with a mean of 4.77 inches and a standard deviation of 0.43 inches. Show all work. (A) What percentage of the apples in this orchard is larger than 4.71 inches? (B) A random sample of 100 apples is gathered ...
*September 2, 2011 by Laynette*

**math**

Empirical rule the authors generac generator produces voltage amounts with a mean of 125.0 volts and a standard deviation of 0.3 volt,and the voltage have a bell-shape distribution.using the empirical rule,what is the approximate percentage of voltage amounts between 124.4 ...
*September 18, 2011 by bibi*

**Statistics**

Olive-Oil producers have expanded to approximately 120 producers statewide. Analysts estimate the average price consumers pay for a bottle of olive oil is $21, with a standard deviation of $2.40. What is the probability that the average price paid by a random sample of 36 ...
*November 17, 2011 by Amber*

**Math**

You invent a new system to make excellent racing tires for the Indianapolis 500/ Your tires are good for an average of 105 miles, with a standard deviation of 7.5 miles. What is the probability that one of your tires can go for at least 44 laps? What is the probability that ...
*July 10, 2012 by Lindsey*

**statistics**

The diameters of grapefruits in a certain orchard are normally distributed with a mean of 6.45 inches and a standard deviation of 0.45 inches. Show all work. (A) What percentage of the grapefruits in this orchard have diameters less than 7.1 inches? (B) What percentage of the ...
*August 28, 2011 by Laynette*

**Statistics**

Assume the body temperature of healthy adults are normally distributed with a mean of 98.2F and a standard deviation of 0.62F. If you have a body temperature of 99.00F, what is your percentile score? Convert 99.00F to a standard score(or a z-score). Is a body temprature of 99....
*August 19, 2010 by Lindsy*

**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? Identify one or ...
*November 15, 2009 by Terra*

**Hypothesis**

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? Identify one or ...
*November 16, 2009 by Terra*

**statistics**

5. A soft drink dispensing machine uses paper cups that hold a maximum of 12 ounces. The machine is set to dispense a mean of 10 ounces of the drink. The amount that is actually dispensed varies. It is normally distributed with a standard deviation of one ounce. (a) What ...
*September 15, 2014 by Sarah *

**stats**

A physical fitness association is including the mile run in its secondary-school fitness test. The time for this event for boys in secondary school is known to possess a normal distribution with a mean of 460 seconds and a standard deviation of 50 seconds. Between what times ...
*November 4, 2014 by elenore*

**statistics**

According to a study of 90 truckers, a trucker drives, on average, 540 miles per day. If the standard deviation of the miles driven per day for the population of truckers is 40, find the 99% confidence interval of the mean number of miles driven per day by all truckers.
*April 13, 2010 by Anonymous*

**RES 341**

A sample of 300 is taken and the sample mean is computed to be 7.65 and the sample standard deviation is 5. Assume the data is ratio level. Compute the 95% confidence interval on the mean. Compute the 3.9% confidence interval on the mean Which confidence interval is more ...
*October 16, 2010 by Meh*

**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...
*February 13, 2015 by slomo*

**math**

Express Courier Service has found that the delivery time for packages is normally distributed with mean 14 hours and standard deviation 2 hours. What should be the guaranteed delivery time on all packages in order to be 95% sure that the package will be delivered before this ...
*January 21, 2013 by Jessica*

**statistics**

In performing a hypothesis test, the null hypothesis is population mean = 6.9 and the alternative hypothesis is population mean ≠ 6.9, a random sample of 16 items is selected. The sample mean is 7.1 and the sample standard deviation is 2.0. The population is ...
*August 17, 2014 by Anonymous*

**Statistical inference**

Suppose the results for stat 201 in 2014 are normally distributed with mean 160 and standard deviation 18 . Find the probability that a random sample of size 36 gives a sample mean value in the following cases Question : between 120 and 220 p(120 < z < 220) p(120-160/3 &...
*August 2, 2015 by Manngopo*

**Statistics**

In a survey, the guess at the mean age for the class had a mean of 21.9 and a standard deviation of 3.03. Given that Normally distributed populations have a first quartile of Z=-0.67 and a third quartile of Z=.67, what does this suggest about whether or not these guesses are ...
*July 14, 2011 by david*

**statistics**

An accounting firm is planning for the next tax preparation season. From last year's returns, the firm collects a systematic random sample of 100 filings. The 100 filings showed an average preparation time of 90 minutes with a standard deviation of 140 minutes. What is the ...
*November 19, 2011 by SHA*

**math**

A bank wishing to determine the average amount of time a customer must wait to be served took a random sample of 100 customers and found that the mean waiting time was 7.2 minutes. Assuming that the population standard deviation is known to be 15 minutes, find the 90% ...
*May 22, 2014 by Anonymous*

**Math**

A random survey of 500 households determines that 20% of the households would do so and that each participating household expects to recycle about 100 cans monthly with a standard deviation of 30 cans. Question (a) What is the 95% confidence interval regarding the percentage ...
*April 21, 2010 by Jamie*

**Statistics**

The international Coffee Association has reported the mean daily coffee consumption for U.S. residents as 1.65 cups. Assume that a sample of 38 people from a North Carolina city consumed a mean of 1.84 cups of coffee per day, with a standard deviation of 0.85 cups. In a two-...
*June 4, 2010 by Julia Brown*

**Statistics**

You are getting ready to take a sample from a large population, and need to determine the appropriate sample size. You are estimating sales at a large chain of department stores. A previous survey from the same population found a standard deviation of $18. What sample size is ...
*July 16, 2012 by Devika*

**Statistic**

Assume that a population is normally distributed with a mean of 100 and a standard deviation of 15. Would it be unusual for the mean of a sample of 3 to be 115 or more? Why or why not? What if the size for each sample was increased to 20? Would a sample mean of 115 or more be ...
*June 9, 2013 by Berry*