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April 25, 2014

Search: Standard Deviation-What?

Number of results: 7,538

math
Suppose the weekly use of gasoline for motor travel by adults in North America is approximately normally distributed, with a mean of 14 gallons and a standard deviation of 6 gallons. What proportion of adults use more than 18 gallons per week?
Monday, April 16, 2012 at 2:43pm by Eliza

Math
2500 students take a college entrance exam. The scores on the exam have an approximate normal distribution with mean u = 52 points and a standard deviation o = 11 points. Estimate the percentage of students scoring 52 points or more. ^ How would you do this?
Tuesday, May 7, 2013 at 11:25pm by Ruth

Statistics
The heights of 18 year old men are approximately normally distributed, with a mean of 67 inches and a standard deviation of 5 inches. What is the probability an 18 year old man selected at random is between 66 and 68 inches? Use FOUR decimal places.
Friday, April 4, 2014 at 1:43pm by Breeanna

chemistry
for the reaction 3C2H2=> C6H6 at 25 C, the standard enthalpy change is -631 KJ and the standard entropy change is -430 J/K. calculate the standard free energy change at 25 C. show all work!
Tuesday, December 4, 2012 at 8:28pm by ashley

Statistics
A recent survey found that 63% of all adults over 50 wear glasses for driving. In a random sample of 80 adults over 50, what is the mean and standard deviation of those that wear glasses?
Tuesday, March 8, 2011 at 7:44pm by Anonymous

statistics
The U.S. Dairy Industry wants to estimate the mean yearly milk consumption. A sample of 20 people reveals the mean yearly consumption to be 72 gallons with a standard deviation of 15 gallons. What is the 99% confidence interval?
Sunday, November 4, 2012 at 5:56pm by Anonymous

statistics
historically, the mean timr to complete this statistics test is 54 minutes with a standard deviation of 9 minutes. how much time should i allow, if my goal is for 95% of the students to be able to complete this test
Saturday, December 1, 2012 at 11:36pm by chavell

stats.
The mean number of bumped airline passengers per day is 1.35 and the standard deviation is 0.25. For a random selection of a group of 40 days, what is the probability that the mean of bumped passengers for the 40 days will be between 1.25 and 1.50?
Monday, March 18, 2013 at 12:51pm by Christina

stats.
The mean number of bumped airline passengers per day is 1.35 and the standard deviation is 0.25. For a random selection of a group of 40 days, what is the probability that the mean of bumped passengers for the 40 days will be between 1.25 and 1.50?
Monday, March 18, 2013 at 3:27pm by Christina

Statistics
Need help! A normal distribution with a mean of 20 and a standard deviation of 2 is evaluated to solve a business problem. What is the probability that the value in the population is between 20 and 30? What is the probability that any value in the population is between 10 and ...
Thursday, August 21, 2008 at 8:12pm by Student

math
A study has shown that 20.05% of all college textbooks have a price of $80 or higher. It is known that the standard deviation of the price is $10. What is the mean price of the college textbooks? Assume the price is normally distributed.
Wednesday, May 25, 2011 at 10:47am by Math

stats
A survey shows that 60% of people who listen to a song on the internet will buy the song. A sample of 30 people who listened to a song is taken. What will be the mean and standard deviation of the number who will buy the song?
Tuesday, March 6, 2012 at 9:20pm by Anonymous

statistics
1. A test has a mean of 50, standard deviation of 10. A. What scores separate the middle 25% from the rest b. What proportion would be expected to score between 45 and 55 c. What proportion would be expected to score 68 and above
Saturday, March 10, 2012 at 3:21pm by Susan

stats
2. The average age of a child in kindergarten is 66 months. The standard deviation is 4 months. If a random child is selected, find the probability that the mean age is: a) Between 64 and 68 months b) Greater than 62 months
Saturday, August 4, 2012 at 10:01am by AMbe

Statistics
A group of 56 randomly selected students have a mean score of 30.8 and a standard deviation of = 4.5 on a placement test. Find a 95% confidence interval for the mean score, , of all students taking the test.
Monday, November 1, 2010 at 3:01pm by Erica

statistics
the average patient lasts 45 minutes on the tilt table. the current patient only lasted 15 minutes. if the standard deviation is 5 minutes. The Zscore that represents the current patients time of 15 minutes should be.
Friday, October 28, 2011 at 4:31pm by wanda

Statistics
A recent survey found that 72% of all adults over 50 wear glasses for driving. In a random sample of 100 adults over 50, what is the mean and standard deviation of the numbe who wear glasses?
Thursday, March 29, 2012 at 3:09pm by Sheila

statistics
The reaction time of subjects to a certain psychological experiment is considered to be normally distributed with a mean of 20 seconds and a standard deviation of 4 seconds. What is the reaction time such that only 10% of subjects are faster?
Wednesday, November 21, 2012 at 1:26pm by michelle

statistics
The reaction time of subjects to a certain psychological experiment is considered to be normally distributed with a mean of 20 seconds and a standard deviation of 4 seconds. What is the reaction time such that only 10% of subjects are faster?
Wednesday, November 21, 2012 at 1:37pm by michelle

statistics
Assume that body temperatures of healthy adults are normally distributed with a mean of 98.2F and a standard deviation of 0.62F. Suppose we take a sample of eight healthy adults. What is the probability that their mean body temperature will be greater than 98.4?
Wednesday, May 8, 2013 at 3:44pm by ali awan

statistics
heights of young adult u.s women are approximatelynormal with mean 64 inches and standard deviation 2.7 inches. What proportion of all u.s. young adult women are taller than 6 feet?
Tuesday, September 7, 2010 at 9:46pm by Diana

calculus
A camera store sells 40 pairs of binoculars per week on average with a standard deviation of 6. What is the probability that the store will sell more than 52 pairs binoculars in any week? 8.28 3.57 7.24 2.28 4.55
Tuesday, November 27, 2012 at 10:03am by tremain

Stats
2. The population standard deviation for the number of rolls before a 1 is observed. Use this result to construct a 90% Z-interval for the mean number of rolls required before a 1 is observed.
Saturday, September 14, 2013 at 12:39am by Me

stat
The average commute time via train from the Chicago O'Hare Airport to downtown is 60 minutes with a standard deviation of 15 minutes. Assume that the commute times are normally distributed. What proportion of commutes would be: longer than 80 minutes? less than 50 minutes? ...
Friday, October 14, 2011 at 11:21pm by des

Q Research
2. The average commute time via train from the Chicago O'Hare Airport to downtown is 60 minutes with a standard deviation of 15 minutes. Assume that the commute times are normally distributed. What proportion of commutes would be: a. longer than 80 minutes? b. less than 50 ...
Sunday, December 9, 2012 at 1:06am by Maurice

Statistics
During September, the average temp of laurel lake is 64.2 degrees. the standard deviation is 3.2 degrees. Assume the variable is normally distributed. For the randomly selected day, find the probability that the temp will be a. above 62 degrees b. below 67 degrees c. between ...
Monday, October 21, 2013 at 5:33pm by Jasmin

statistics
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 ounces?
Sunday, March 28, 2010 at 8:48am by Anonymous

Statstics
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 <21 ounces?
Sunday, March 28, 2010 at 8:50am by Anonymous

chemistry 2
for the reaction 2C2H2(g)=>C6H6(l) at 25 C, the standard enthalpy change is -631 kJ and the standard entropy change is -430 J/K. calculate the standard free energy change at 25 C. show all work Help please!
Wednesday, December 5, 2012 at 3:07am by concerned chem student

chemistry 2
for the reaction 2C2H2(g)=>C6H6(l) at 25 C, the standard enthalpy change is -631 kJ and the standard entropy change is -430 J/K. calculate the standard free energy change at 25 C. show all work Help please!
Wednesday, December 5, 2012 at 3:24pm by concerned chem student

college Statistics
A distribution with a mean of 200 units, a standard deviation of 40 units, a minimum value of 4 units and a maximum value of 245 units is A. Positively skewed B. Negatively skewed C. "Bell-shaped" D. Bi-modal
Tuesday, December 8, 2009 at 8:55am by Adria

Statistics
What is the 10th percentile, n of group of people's pulse rates, where X = pulse rates of group of people, for which the mean is 73 and the standard deviation is 8? Assume a normal distribution. (Round your answer to the nearest whole number.) n = .
Sunday, February 19, 2012 at 12:27pm by Anonymous

Probability and Statistics
The ACT scores of applicants to college are approximately normally distributed with a mean of 20.3 and a standard deviation of 3.1. If a random sample of 20 applicants to college is chosen find the probability that their average ACT score will be 19 and 21.
Sunday, April 29, 2012 at 8:09pm by Kim

Statistics
A researcher found a sample proportion of 0.94 for estimating the population proportion of freshmen at a university who had Facebook accounts. If the standard deviation of the sampling distribution of the sampling proportion is 0.02, what is a 95% confidence interval for the ...
Friday, May 18, 2012 at 5:09pm by Mary

Data Management
The teacher of a Data Management class, in which the class average is 68% with a standard deviation of 8.5%, has offered to help up to 10% of the students after school with their projects. Using the normal distribution, how should the teacher decide who will get help? Explain.
Wednesday, May 23, 2012 at 8:53pm by Michael Cannataroe

statistics
The authors state that the heights of women in North America are normally distibuted with a mean of 65.0 and a standard deviation of 3.5 inches. I am 64.5 inches. Using the parameters above, what percent of women in North America are shorter than I am?
Monday, July 2, 2012 at 6:23pm by Maria

statistics
from a normally distributed infinite number of iron bars lengths with a mean and standard deviation as 4 ft. and 0.6 ft. respectively, a sample of 100 bars is taken. if the sample mean is 4.2 ft., can the sample be called a truely random sample?
Monday, April 22, 2013 at 3:39am by aman

probability and statistics
An electrical firm manufactures light bulbs that have a usuable life that is normally distributed with a mean of 1000 hours and a standard deviation of 80 hours. Find the probability that a package of 4 bulbs would last at least 4400 hours.
Sunday, April 29, 2012 at 7:57pm by Kim

Statics
A random sample of 100 cans of peaches has an observed mean weight of 48.5 ounces and a standard deviation of 2.4 ounces. Determine the lower limit of the 95% interval for the true mean weight. The can label says that the can weights 48 ounces. Comment on this claim.
Saturday, December 1, 2012 at 11:36am by Heather

stat.
The average age of a vehicle registered in the United States is 8 years, or 96 months. Assume the standard deviation is 16 months. If a random sample of a group of 48 vehicles is selected find the probability that the mean of the groups age is between 90 and 100 months.
Sunday, March 17, 2013 at 5:36pm by chris

statistics
The average age of a vehicle registered in the United States is 8 years, or 96 months. Assume the standard deviation is 16 months. If a random sample of a group of 48 vehicles is selected find the probability that the mean of the groups age is between 90 and 100 months.
Sunday, March 17, 2013 at 9:12pm by tony

statistics
The Redsox were accused of cheating their soda customers by not putting enough soda in the 12 ounce cup. When 15 cups were selected at random, they were found to have a mean of 11.7 ounces with a standard deviation of 0.5 ounces. At the .01 significance level, test the claim ...
Friday, December 10, 2010 at 1:29am by Veronica Marie

Statistics
The mean graduation time is 5 years with a standard deviation of 6 months for the Monte Carlo College, in which the graduation time is related to the grade of the students. The class size is normally 40. Calculate how many students may graduate by the end of the fourth year. ...
Wednesday, October 12, 2011 at 5:39am by Diana

Statistics & Probability
If X is a normal random variable with mean 11, and if the probability that X is less than 12.10 is .72 , then what is the standard deviation of X? Select one: a. 3.00 b. 6.25 c. 2.50 d. 1.25 Please note that the answer for the above is stated as c.2.50. However, my answer ...
Friday, January 4, 2013 at 6:57pm by Alia

Help with statistics
The design tolerance thickness for an automotive part is 55mm to 65mm. If the process mean thickness is 61mm with a standard deviation of 2.3mm, then what percentage of the sheets will be acceptable?(What percentage will fall within the design tolerence?) Assume that the ...
Tuesday, April 16, 2013 at 2:53pm by Bettie

Statistics
The design tolerance thickness for an automotive part is 55mm to 65mm. If the process mean thickness is 61mm with a standard deviation of 2.3mm, then what percentage of the sheets will be acceptable?(What percentage will fall within the design tolerence?) Assume that the ...
Thursday, April 18, 2013 at 2:53pm by john

Statistics
The manufacturer of a new compact car claims the miles per gallon (mpg) for the gasoline consumption is mound-shaped and symmetric with a mean of 24.6 mpg and a standard deviation of 11.2 mpg. If 30 such cars are tested, what is the probability the average mpg achieved by ...
Tuesday, April 23, 2013 at 11:24am by Terrance

statistics
The manufacturer of a new compact car claims the miles per gallon (mpg) for the gasoline consumption is mound-shaped and symmetric with a mean of 24.6 mpg and a standard deviation of 11.2 mpg. If 30 such cars are tested, what is the probability the average mpg achieved by ...
Sunday, May 5, 2013 at 8:15pm by james

Math Models
The scores on a standardized test are normally distributed with the mean of 750 and standard deviation 70. Find the probability that a score is more than 890. This is from my Math Models class. I am not taking Statistics. Please someone show me how to do answer this-I don't ...
Wednesday, May 22, 2013 at 2:36am by Denise

Statistics
The weights of male babies less than 2 months old in the United States is normally distributed with a mean of 11.5 pounds and a standard deviation of 2.7 pounds. Find the 80th percentile score for these weights. I don't have a table, I have to figure it out using the TI-84 ...
Tuesday, February 25, 2014 at 7:13pm by Jeri Jackson

Math (Statistics)
The SAT scores of a certain population of students are approximately normally distributed with a mean and standard deviation of 1000 and 200 points, respectively. The probability that a student selected at random from the population has an SAT score between 800 and 1200 ...
Friday, February 28, 2014 at 3:20pm by Nakia Speaks

statistics
assume that blood pressure readings are normally distributed with a mean of 111 and standard deviation of 7. A researcher wishes to select people for a study but wants to exclude the top and bottom 10 percent. What would be the upper and lower readings to qualify people to ...
Monday, March 24, 2014 at 2:59am by jessica

Statistics
I need help figuring out these two problems. I think I have the right idea about solving them but I'm not exactly sure. 8. Two companies market new batteries targeted at owners of personal music players. DuraTunes claimes a mean battery life of 11 hours, while RockReady ...
Saturday, November 10, 2007 at 4:02pm by Courtney

Finance
I need help on this study problem.----- A firm computes the probability distribution of possible net present values for a project and finds that it has an expected value of $125,000 and a standard deviation of $75,000. Assuming that the distribution of net present value is ...
Thursday, November 2, 2006 at 12:22am by Jenny

math
Under what conditions might it be appropriate to use the mean? Median? Mode? When the median and mean are substantially different, what does that tell you about the data? What information does the range and standard deviation provide about the data?
Tuesday, December 15, 2009 at 1:41pm by Jama

Stats
A group of 56 randomly selected students have a mean score of 30.8 and a standard deviation of 4.5 on a placement test. Find a 95% confidence interval for the mean score, , of all students taking the test. (Note: is unknown.)
Monday, November 1, 2010 at 2:25pm by Erica

statistics
determine the probability that a sample of 49 boxes will have a mean weight below 365 grams. past records show that the population mean is 368 grams and the population standard deviation is 7. the probability will be between.
Wednesday, November 30, 2011 at 11:08pm by wanda

statistics
A person scores 140 on an intelligence test with mean 100, a standard deviation of 15, and a reliability of 0.6. We can be 95% certain that this person's TRUE intelligence is between ____ and ____. Pick the answer that is closest to the correct answer
Monday, December 12, 2011 at 1:59pm by chinwe

Statistics
Suppose that the travel time from your home to your office is normally distributed with a mean of 40 minutes and standard deviation of 7 minutes. If you want to be 95% certain that you will not be late for an office appointment at 1:00pm, what is the latest time that you ...
Tuesday, March 20, 2012 at 10:26pm by Brad

Statistics
The lengths of pregnancies are normally distributed with a mean of 273 days and a standard deviation of 20 days. If 64 women are randomly selected, find the probability that they have a mean pregnancy between 273 days and 275 days.
Sunday, February 10, 2013 at 4:32pm by Jane

Statistics
The weights of the fish in a certain lake are normally distributed with a mean of 15lbs. and standard deviation of 6lbs. If a sample of 5 fish are taken from the lake, find the probability their means weights are between 12.6 lbs. and 18.6 lbs.
Wednesday, October 30, 2013 at 7:05pm by Amy

Statistics
A random sample of 14 college female students revealed their average height was 66.1 inches. a) How many students should be in a samle if a 95% confidence interval is to have a margin of error of only plus/minus 1 inch? Is that the only information you were given? Were you not...
Monday, July 30, 2007 at 5:01pm by Kasey

Statistics
A group of statistics students decided to conduct a survey at their university to find the average (mean) amount of time students spent studying per week. Assuming a standard deviation of 3 hours, what is the required sample size if the error should be less than hour with a ...
Sunday, September 5, 2010 at 4:44pm by Robin

math please help me
Select a variable (mean, proportion, variance or standard deviation) of interest to you and collect data consisting of at least 30 values. Define the variable. Define the population. Describe how the sample was selected. Use Microsoft Excel (and MegaStat if at all possible) to...
Monday, April 4, 2011 at 6:07pm by ibrahim

Statistics
A random sample of 10 independent observations from a normally distributed population yielded the following values 51, 53, 49, 43, 47, 46, 45, 30, 60, 52. a) Estimate the standard deviation of the sampling distribution of means for samples like this one. b) Using = .05, test...
Sunday, May 5, 2013 at 2:25pm by Deb

Quantative reserach
1. The average commute time via train from the Chicago O'Hare Airport to downtown is 60 minutes with a standard deviation of 15 minutes. Assume that the commute times are normally distributed. What proportion of commutes would be: a. longer than 80 minutes? b. less than 50 ...
Sunday, November 13, 2011 at 8:27am by Michael

Statistics
SAT scores are normally distributed with a mean of 500 and a standard deviation of 100. Using the formula for σM, what will σM be when a. the sample size is 25 b. the sample size is 121, and c. the sample size is 400?
Monday, November 18, 2013 at 8:04pm by Mikos

statistics
Assume the body temperture of healthy adults are normally distributed with a mean of 98.20 degrees F and a standard deviation of 0.62 degrees F... a. If you have a body temperture of 99.00 degrees F, what is your percentile score? b. Convert 99.00 degrees F to a standard score...
Saturday, May 8, 2010 at 4:28pm by Jamie

statistics
the life expectancy of lung cancer patient treated with a new drug is normally distributed with a mean of 4 years and a standard deviation of 10 months what is the probability that a randomly selected lung cancer patient will last more than 5 years
Sunday, March 28, 2010 at 11:08am by yolanda

statistics
The average age of a vehicle registered in the U.S. is 8 years, or 96 months. If a random sample of 36 vehicles is selected, find the probability that the mean of their age is between 98 and 100 months. Assume the standard deviation for the population is 15. (sample mean)
Monday, December 20, 2010 at 2:14pm by Jana

MATH
Suppose that people's heights (in centimeters) are normally distributed, with a mean of 175 and a standard deviation of 6. We find the heights of 80 people. (a) How many would you expect to be between 168 and 182 cm tall? (b) How many would you expect to be taller than 170 cm?
Wednesday, August 24, 2011 at 3:40pm by Lee Ann

math
Suppose that people's heights (in centimeters) are normally distributed, with a mean of 175 and a standard deviation of 6. We find the heights of 40 people. (a) How many would you expect to be between 169 and 181 cm tall? 1 (b) How many would you expect to be taller than 170 ...
Wednesday, August 24, 2011 at 8:38pm by apryl

math
Suppose that people's heights (in centimeters) are normally distributed, with a mean of 175 and a standard deviation of 6. We find the heights of 40 people. (a) How many would you expect to be between 169 and 181 cm tall? (b) How many would you expect to be taller than 170 cm?
Thursday, August 25, 2011 at 12:38pm by apryl

alegbra
Suppose that people's heights (in centimeters) are normally distributed, with a mean of 175 and a standard deviation of 6. We find the heights of 60 people. (a) How many would you expect to be between 167 and 183 cm tall? (b) How many would you expect to be taller than 170 cm?
Sunday, August 28, 2011 at 2:21pm by apryl

statistics
Suppose that people's heights (in centimeters) are normally distributed, with a mean of 165 and a standard deviation of 6. We find the heights of 80 people. (a) How many would you expect to be between 159 and 171 cm tall (b) How many would you expect to be taller than 160 cm
Tuesday, November 29, 2011 at 12:02pm by gertrude

statistics
Suppose that people's heights (in centimeters) are normally distributed, with a mean of 165 and a standard deviation of 6. We find the heights of 80 people. (a) How many would you expect to be between 159 and 171 cm tall (b) How many would you expect to be taller than 160 cm
Tuesday, November 29, 2011 at 12:03pm by gertrude

statistics
dole pineapple inc. is concerned that the 16 ounce cans are overfilled. assume the standard deviation is .03 onces. a random sample of 50 cans has a mean weight of 16.05 ounces. at the 5% level of significance can we conclude that the mean weight is > than 16 ounces. what ...
Monday, April 2, 2012 at 12:07am by dimitra

statistics
the mean age at which men in the united states marry for the first time follows the normal distribution with a mean of 24.5 years. the standard deviation is 2.8 years. for a rabdom sample of 59 men, what is the likelihood that the age they were married were less than 25
Wednesday, April 25, 2012 at 4:41pm by Vondon

math
In a random sample of 1,000 exams, the average score was 500 points with a standard deviation of 80 points. Find the interval about the sample mean such that the probability is 0.90 that the mean number lies within the interval.
Friday, May 25, 2012 at 12:55pm by King

ALGEBRA
Suppose that people's heights (in centimeters) are normally distributed, with a mean of 175 and a standard deviation of 6. We find the heights of 60 people. (a) How many would you expect to be between 167 and 183 cm tall? (b) How many would you expect to be taller than 170 cm?
Sunday, June 3, 2012 at 8:35pm by Urgen please help

ALGEBRA
Suppose that people's heights (in centimeters) are normally distributed, with a mean of 165 and a standard deviation of 6. We find the heights of 60 people. (a) How many would you expect to be between 159 and 171 cm tall? (b) How many would you expect to be taller than 160 cm?
Sunday, June 10, 2012 at 2:15am by Mike

ALGEBRA
Suppose that people's heights (in centimeters) are normally distributed, with a mean of 165 and a standard deviation of 6. We find the heights of 60 people. (a) How many would you expect to be between 159 and 171 cm tall? (b) How many would you expect to be taller than 160 cm?
Sunday, June 10, 2012 at 9:11pm by Urgen please help

statistics
Faculty in the psychology department at APUS consume an average of 5 cups of coffee per day with a standard deviation of 1.5. The distribution is normal. How many cups of coffee would an individual at the 25th percentile drink per day? A. 4 B. 5 C. 6 D. 7
Wednesday, August 15, 2012 at 12:35pm by StudentD

math
Suppose that people's heights (in centimeters) are normally distributed, with a mean of 165 and a standard deviation of 6. We find the heights of 60 people. (a) How many would you expect to be between 158 and 172 cm tall? 1 (b) How many would you expect to be taller than 160 ...
Tuesday, August 28, 2012 at 12:41pm by Anonymous

math
Suppose that people's heights (in centimeters) are normally distributed, with a mean of 165 and a standard deviation of 6. We find the heights of 60 people. (a) How many would you expect to be between 158 and 172 cm tall? 1 (b) How many would you expect to be taller than 160 cm?
Wednesday, August 29, 2012 at 5:00pm by Anonymous

math
Suppose that people's heights (in centimeters) are normally distributed, with a mean of 165 and a standard deviation of 6. We find the heights of 60 people. (a) How many would you expect to be between 158 and 172 cm tall? 1 (b) How many would you expect to be taller than 160 ...
Wednesday, August 29, 2012 at 5:03pm by Anonymous

statistics
mean=20, standard deviation =6.Use the emperical rule to estimate the probabilty that a randomly chosen patient had to wait more than 26 min. Of 2000 patients, estimate the # of patient having to wait more than 26 mins
Monday, November 12, 2012 at 9:59am by Anonymous

math
The mean amount spent by a family of four on food per month is $550 with a standard deviation of $85. Assuming that the food costs are normally distributed, what is the probability that a family spends less than $410 per month?
Friday, November 16, 2012 at 11:28am by Anonymous

Math
Suppose that people's heights (in centimeters) are normally distributed, with a mean of 175 and a standard deviation of 6. We find the heights of 80 people. (a) How many would you expect to be between 167 and 183 cm tall? (b) How many would you expect to be taller than 170 cm?
Friday, December 21, 2012 at 9:19am by Tammy Jones

Algebra
Suppose that people's heights (in centimeters) are normally distributed, with a mean of 175 and a standard deviation of 6. We find the heights of 80 people. (a) How many would you expect to be between 167 and 183 cm tall? (b) How many would you expect to be taller than 170 cm?
Friday, December 21, 2012 at 9:54am by DC

algebra 2
Students at a high school all took the same English test. The scores are approximately normally distributed with a mean of 77 and a standard deviation of 9. If 2500 students took the test, approximately how many scored above 86 or below 68%?
Monday, April 8, 2013 at 5:09pm by Lea

statistics
Professor Smith gave a final exam in her history class. The scores on the final exam are normally distributed with a mean of 75 and a standard deviation of 6. If Professor Smith wishes to give As to the top 4%, what would be the cutoff score be for As? a. 90.0 b. 87.3 c. 85....
Monday, April 14, 2014 at 11:25pm by Sally

statistics
A runner has a average race time of 4.5 minutes with a standard deviation of 0.14. What time do 75% of his race times fall and what time would he have to achieve to be in the top 5% of his race times?
Thursday, October 30, 2008 at 7:13pm by Ken

Business
For a continuous random variable x, the population mean and the population standard deviation are 80 and 15 respectively. You extract a sample of 25 elements from this population. The mean of the sampling distribution of the sample mean is
Sunday, May 16, 2010 at 3:10pm by Donna

calculus
A MANUFACTURE OF LIGHTBULBS HASS SAMPLED 40 BULBS IN ORDER TO DETERMINE THE POPULATION MEAN LIFE OF THE BULBS. tHE SAMPLE MEAN WAS 1200 HOURS WITH A STANDARD DEVIATION OF 100. tHE MANUFACTURER WOULD LIKE TO KNOW, WITH 95% CONFIDENCE, THE INTERVAL VALUES FOR THE POPULATION MEAN.
Friday, February 27, 2009 at 2:10am by PHILLIP

statistics
Answer the question(s) based on the following situation: 150 students in a math class take the final exam. The scores on the exam have an approximately normal distribution with center = 65 and standard deviation = 10.The third quartile of the scores on the exam is ...
Wednesday, March 17, 2010 at 4:28pm by Whitney

STATISTICS HELP
The lifetime of a disk drive head is normally distributed with a population mean of 1000 hours and standard deviation of 120 hours. Determine the probability that the average lifetime for 9 disk drives will exceed 940 hours. Need to see work!
Monday, November 8, 2010 at 7:02pm by Heather

stat
A company installs 5000 light bulbs, each with an average life of 500 hours, standard deviation of 100 hours, and distribution approximated by a normal curve. Find the percentage of bulbs that can be expected to last the period of time. 77) At least 500 hours
Thursday, November 25, 2010 at 11:34am by Anonymous

statistics
Health Club Schedule The time per workout an athlete uses a stairclimberis normally distributed with a mean of 20 mins and a standard deviation of 5 min. An athlete is randomly selected. Find the probability that the athlete uses a stairclimber between 20 and 28 mins.
Friday, February 11, 2011 at 12:19am by Jessica

statistics
The weights of steers in a herd are distributed normally. The standard deviation is 200 lbs and the mean steer weight is 1200 lbs. Find the probability that the weight of a randomly selected steer is less than 1560 lbs. (Round your answer to 4 places).
Wednesday, April 25, 2012 at 3:18pm by Anonymous

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