# statistics/mean and standard deviation

25,527 results

statistics
Kindergarten children have heights that are approximately distributed normal. A random sample of size 20 is taken and the mean x and the standard deviation s are calculated ( x = 40 inches and s = 3). a. Is there sufficient evidence to indicate that the mean of kindergarten ...

Statistics (42)
A simple random sample of 60 items resulted in a sample mean of 96. The population standard deviation is 16. a. Compute the 95% confidence interval for the population mean (to 1 decimal). ( , ) b. Assume that the same sample mean was obtained from a sample of 120 items. ...

Math
I need help with this these two problem PLEASE!!! For a population with a mean of μ  80 and a standard deviation of   12, find the z-score corresponding to each of the following samples. a. M  83 for a sample of n  4 scores b. M  83 for a sample of n  16 scores c. ...

statistics
A maintenance supervisor is comparing the standard version of an instructional booklet with one that has been claimed to be superior. An experiment is conducted in which 26 technicians are divided into two groups, provided with one of the booklets, then given a test a week ...

Statistics
The average mpg usage for a 2004 Ford Expedition 2WD for a sample of 10 tanks of gas was 17.0with a standard deviation of 0.8. For a Ford Explorer 2WD, the average mpg usage for a sample of 10 tanks of gas was 18.5 with a standard deviation of 1.0. (a) Assuming equal variances...

Math
Susan owns a chocolate store. She sells her chocolate by the gram and needs to compare the weights of two chocolate batches. She randomly selects 100 pieces from each batch. The distrubition of both samples are normal. Batch 1 - (Mean Weight) 56 grams Standard Deviation - 6 ...

statistics
A normal distribution has a mean of 20 and a standard deviation of 2. If you convert every score in the distribution to Z scores, which of the following statements would be true of the resulting distribution?

statistics research
What proportion of adults use between 15 and 23 gallons of gas per week if it is normally distributed with a mean of 16 gallons and a standard deviation of 5 gallons?

statistics
Waiting times at a doctor office are normally distributed with a mean of 35 minutes, and a standard deviation of 10 minutes. 25% of the patients have to wait less than how many minutes?

chemistry
Your team performed replicate analyses of a sample and obtained an average 18.54 mM concentration with a relative standard deviation of 4.0%. If you later discover that a systematic error was made by a factor of 2 and the mean concentration should have been 9.27 mM, what is ...

statistics
The mean of a normal distribution is 400 pounds. The standard deviation is 10 pounds. What is the area between 415 pounds and the mean of 400 pounds? The area between the mean and 395?

Stats
I am working on a review sheet and got everything except for this one. I am not sure whether to use z or t. The number of hours per week that high school juniors watch TV is normally distributed with a mean of 8 hours and a standard deviation of 2 hours. If 100 students are ...

college math
20. Calculate the range, variance, and standard deviation of the following data set: 5, 5, 6, 6, 6, 8, 8, 8, 8, 10, 10, 11, 12, 12, 20 (Points: 5) Range = 15; Variance = 225; Standard Deviation = 7.5 Range = 3.85; Variance = 14; Standard Deviation = 3.74 Range = 20; Variance...

math
Four boxes of cereal are to be selected at random from a continuous process that fills boxes labeled "Contents: 340 g." The contents of the first three boxes are found to weigh 339.0g, 337.7 g, and 338.9 g. (a) What minimum weight of cereal must the fourth box contain so that ...

Statistics
A study was conducted in order to estimate u, the mean number of weekly hours that U.S. adults use computers at home. Suppose a random sample of 81 U.S. adults give a mean weekly computer usage time of 8.5 hours and that from prior studies , the population standard deviation ...

Psychology
Twenty students randomly assigned to an experimental group receive an instructional program; 30 in a control group do not. After 6 months, both groups are tested on their knowledge. The experimental group has a mean of 38 on the test (with an estimated population standard ...

chemistry
#1 A pipet delivers 10.5, 10.3, 10.9 and 10.7 ml (a) find the mean volume and deviation from the mean for each and calculate the average deviation from the mean (b) calculate the relative deviation (in %) for this set of data. Relative deviation (%) = (average deviation from ...

chemistry
#1 A pipet delivers 10.5, 10.3, 10.9 and 10.7 ml (a) find the mean volume and deviation from the mean for each and calculate the average deviation from the mean (b) calculate the relative deviation (in %) for this set of data. Relative deviation (%) = (average deviation from ...

Statistics/Probability
Bottles of water are labeled as containing 12 oz. Statistics students weighted the content of 7 randomly chosen bottles and found the mean weight to be 12.15 oz. Assume that bottles of water are filled so that the actual amounts are normally distributed with a mean of 12.00 oz...

Math help
Can someone give me simple formulas for the below problems. What I found is too confusing. A sample of 145 values is randomly selected from a population with mean, ì, equal to 45 and standard deviation, ó, equal to 23. (Give your answers correct to one decimal place.) (a) ...

statistics
For a particular sample of 71 scores on a psychology exam, the following results were obtained. First quartile = 58 Third quartile = 86 Standard deviation = 8 Range = 50 Mean = 75 Median = 72 Mode = 74 Midrange = 55

statistics
a study of 40 professors showed they spent on average 13.6 minutes correcting a student papers. Given a standard deviation of 17, the 90% confidence interval of the mean time for all the test papers is what?

statistics
the mean and the standard deviation of the wages of 1000 factory workers are \$20,600 and \$2,400 respectively. if a worker's annual wage is \$20,000, find and interpret the worker's sample z-score.

Statistics
The lifetime of television produced by the Hishobi Company are normally distributed with a mean of 75 months and a standard deviation of 8 months. If the manufacture wants to have to replace only 1% of its televisions, what should its warranty be?

statistics
How many infants should you sample if you want a margin of error of 10 minutes for a 95% confidence interval about the mean amount of sleep they get per day if the population standard deviation is assumed to be 96 minutes?

Statistics
Suppose. Population of test-scores is normally distributed with mean 65 and standard deviation 13 x~n (65,13) if you select a test at randome what is the probability that the score is below 60 or that it is between 65 and 70 please show work!

statistics
Assume that adults have IQ score that are normally distributed with a mean of 105 and a standard deviation 20. Find P, which is the IQ score separating the bottom 10% from the top 90%. Round to the nearest hundredth as needed.

statistics
Suppose the average body temp is 98.6 assume the variable is normally distributed with a standard deviation of .74 degrees. suppose a sample of 100 is taken. what is the probability that the mean is below 98.4??? Between 98.5 AND 98.7??

statistics
Assume that a standardized test is designed to have the mean score of 100 and the standard deviation of 15. At the 95% confidence interval, how large does the sample size have to be if the margin of error is to be 3 points?

Statistics
Assume that a standardized test is designed to have the mean score of 100 and the standard deviation of 15. At the 95% confidence interval, how large does the sample size have to be if the margin of error is to be 3 points?

statistics
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 the 20 scores is 1.30. Also, the sample data appear to have a bell-shaped distribution. Construct the 95% confidence interval for ...

statistics
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 the 20 scores is 1.30. Also, the sample data appear to have a bell-shaped distribution. Construct the 95% confidence interval for ...

statistics
the average score on the statistics quiz was a 70, and there was a standard deviation of 10 points. If the z-socre was -1.0 what is the percentile rank?

statistics
The length of country and western songs is normally distributed and has a mean of 200 seconds and a standard deviation of 30 seconds. Find the probability that a random selection of 9 songs will have mean length of 186.30 seconds or less. Assume the distribution of the lengths...

Algebra
Over 350 students took a college calculus final exam. the scores of the students follow a normal distribution. using the information given below, determine the mean and the standard deviation for the students'scores. Give your answers to the nearest tenth of a percent. 1. 32% ...

Statistics
A study is being planned to estimate the mean number of semester hours taken by students at a college. The population standard deviation is assumed to be o=4.7 hours. How many students should be included in the sample to be 99% confident that the sample mean is within one ...

statistics
A bank’s loan officer rates applicants for credit. The ratings are normally distributed with a mean of 175 and a standard deviation of 15. If an applicant is randomly selected, find the probability of a rating that is between 150 and 200.

statistics
If the score on a test has a mean of 52 and a standard deviation of 5, what is the z-score for a score of 58

statistics
Heights of fences are normally distributed with a mean of 52 inches and a standard deviation of 4 inches. Find the probability that one randomly selected fence is under 54 inches.

statistics
The heights of South African men are normally distributed with a mean of 64 inches and a standard deviation of 2 inches. a) What is the probability that a randomly selected woman is taller than 66 inches?

statistics
The volumes of soda in quart soda bottles are normally distributed with a mean of 32.3 oz and a standard deviation of 1.2 oz. What is the probability that the volume of soda in a randomly selected bottle will be less than 32 oz?

stats
Our students were asked to rate their admiration of Hillary Rodham Clinton on a scale of 1 to 7. They were asked to rate their Jennifer Lopez and Venus Williams on a scale of 1 to 7. The mean rating of Clinton was 4.06 with a standard deviation of 1.70. The mean rating of ...

stats
Our students were asked to rate their admiration of Hillary Rodham Clinton on a scale of 1 to 7. They were asked to rate their Jennifer Lopez and Venus Williams on a scale of 1 to 7. The mean rating of Clinton was 4.06 with a standard deviation of 1.70. The mean rating of ...

Statistics
Suppose the mean income of 35-year-olds in the US is \$25,000. A random sample of 150 35-year-olds in California results in a sample mean income of \$26,600 and a sample standard deviation of \$3800. At the 5% significance level, ca we conclude that the true mean income of 35-...

statistics definition
i have to find definitions and describe 208 words in my statistics class and for one of them it says: describe the deviation from a pattern of a graph. i don't actually get what it's asking me. i don't think it's pattern becuase i already have the definition for that. when it ...

Stats
Dee's store monthly sales for April, May, June are three independent random variables with means and variances as follow: April: Mean: \$9500 Variance: \$1250 May: Mean: \$7400 Variance: \$1425 June: Mean: \$8600 Variance: \$1610 a) find the mean and standard deviation of the total ...

Statistics (urgent)
A beverage comopany uses a machine to automatically fill 1-liter bottles. Assume that the population of volumes is normally distributed. The company wants to estimate the mean volume of water to within 1 ML. Determine the minimum sample size required to construct a 95% ...

80 U2 songs (in seconds) were selected at random. Assume that the data is normally distributed and that the bands entire collection of songs has a mean and standard deviation equal to those calculated(mean=289.7 or 290, standard deviation= 76.8 or 77). What percentage of U2 ...

math
On a standardized test, Ann received a score of 85, which was exactly 2 standard deviations about the mean. If the standard deviation for the test is 4, what is the mean for this test?

stats(help)
Our students were asked to rate their admiration of Hillary Rodham Clinton on a scale of 1 to 7. They were asked to rate their Jennifer Lopez and Venus Williams on a scale of 1 to 7. The mean rating of Clinton was 4.06 with a standard deviation of 1.70. The mean rating of ...

math
sample of 40 observations is selected from one population with a population standard deviation of 4.6. The sample mean is 101.0. A sample of 47 observations is selected from a second population with a population standard deviation of 4.0. The sample mean is 99.3. Conduct the ...

statistics
the breaking strength of a cable known to be normally distributed with a mean of 4000kg and a standard deviation of 25kg.The manufacture prefers that at least 95% of its products meet a strength requirement of 4050 kg.Is this requirement being met? If not, by changing the ...

statistics
the breaking strength of a cable known to be normally distributed with a mean of 4000kg and a standard deviation of 25kg.The manufacture prefers that at least 95% of its products meet a strength requirement of 4050 kg.Is this requirement being met? If not, by changing the ...

statistics
the breaking strength of a cable known to be normally distributed with a mean of 4000kg and a standard deviation of 25kg.The manufacture prefers that at least 95% of its products meet a strength requirement of 4050 kg.Is this requirement being met? If not, by changing the ...

Statistics
A quality control inspector wants to estimate the mean inside diameter of the washers produced by a certain machine. A preliminary sample indicates that the inside diameters have a standard deviation of 0.30 millimeters. What sample size does he need to estimate the mean to ...

Statistics
A survey is being planned to determine the mean amount of time corporation executives watch television. A pilot survey indicated that the mean time per week is 12 hours, with a standard deviation of 3 hours. It is desired to estimate the mean viewing time within one quarter ...

Statistics
A private medical clinic wants to estimate the true mean annual income of its patients. The clinic needs to be within \$500 of the true mean. The clinic estimates that the true population standard deviation is around \$2,300. If the confidence level is 95%, find the required ...

statistics defns
What is the coefficient of variation and how do I calculate it from a dataset? coefficient of variation is simply the standard deviation divided by the mean.

statistics
2. Children’s heights are normally distributed with a mean of 100 cm and a standard deviation of 6 cm. What proportion of children’s heights is smaller than 94?

statistics
2.Children’s heights are normally distributed with a mean of 100 cm and a standard deviation of 6 cm. What proportion of children’s heights is smaller than 94?

Statistics
Calculate the following: a) Determine the sample size necessary to estimate a population mean to within 1 with a 90% confidence given that the population standard deviation is 10. b) Suppose that the sample was calculated at 150. Estimate the population mean with 90% confidence.

statistics
a random sample of 20 prices for summer sleeping bags was taken with a sample mean of \$83.75 and a sample standard deviation of \$29.97 a. Find a 95% confidence interval for the mean price of all summer sleeping bags. b. what is m i.e., what is the margin of error?

Stats
Cans of regular Coke are labeled as containing 12. Statistics students weighted the content of 10 randomly chosen cans, and found the mean weight to be 12.1. Assume that cans of Coke are filled so that the actual amounts are normally distributed with a mean of 12 and a ...

Stats
Exercise 6-8 The Downtown Parking Authority of Tampa, Florida, reported the following information for a sample of 235 customers on the number of hours cars are parked and the amount they are charged. Number of Hours Frequency Amount Charged 1 18 \$3 2 33 7 3 49 10 4 44 15 5 34 ...

statistics
GIVEN THE FOLLOWING STATISTICAL VARIABLES A:m(A)=5 B:m(B)=13 var(A)=25 Var(B)=6 1.calculate mean of Z= 4B-2A 2.Calculate the Standard Deviation assuming cov (A,B)=0

statistics
can you explain this to me please? Consider the binomial distribution where n = 11 and p = 0.05. Find the mean and standard deviation of this binomial distribution.

statistics
a rocket club makes its own rockets. The rockets go to a mean height of 1100 feet with a standard deviation of 60 feet. if the club fires 36 rockets, what is probability that the mean heights of the rockets will be greater than 1080p feet

math
A set of data items is normally distributed with a mean of 70. Convert the data item to a z-score, if the standard deviation is as given. data item: 80; standard deviation: 15

statistics
the following data represents the percentages of family income allocated to groceries for a sample of 50 shoppers: percentage of family income #of shoppers 10-19 6 20-29 14 30-39 16 40-49 11 50-59 3 1.calculate the value of mean 1.1 meadian percentage of family income spent on...

statistics
The Frayed Nerves Anxiety Scale (FNAS) is used to measure the anxiety level of people on a scale from 0 to 1000. Four students were randomly chosen and given the FNAS before their second exam. Their scores were 700, 653, 740, and 707. The standard deviation sigma of the test ...

Statistics
Find the margin of error for a 95% confidence interval for estimating the population mean when the sample standard deviation equals 100, with a sample size of (i) 400, (ii) 1600. What is the effect of the sample size? (b) Find the margin of error for estimating the population ...

statistics
A student scored 84 points on a test where the mean score was 79 and the standard deviation was 4. Find the student's z score, rounded to 2 decimal places

statistics
IQ scores are normally distributed with a mean u = 100 and a standard deviation o =15. Based on distribution, determine % of IQ scores between 100 and 120 =

Statistics
What is the appropriate sample size for a confidence interval around the sample mean if you want a margin of error of 0.8 with 95% confidence and a population standard deviation of 12.

statistics
The test scores of students in a class test have a mean of 65 and with a standard deviation of 8. What is the probable percentage of students scored more than 70?

Statistics
How do I answer: A normal distribution has a standard deviation equal to 39. What is the mean of this normal distribution if the probability of scoring above x = 209 is 0.0228

statistics
On a entrance exam, the mean was 50 and standard deviation was 5. If Ricky's z-score was -1.5, what was his exam score? I don't have a clue how to start to answer this question...

math
A sample of 148 of our statistics students rated their level of admiration for Hillary Rodham Clinton on a scale of 1 to 7. The mean rating was 4.06, and the standard deviation was 1.70. (For this exercise, treat this sample as the entire population of interest.) a. Use these ...

math
A sample of 148 of our statistics students rated their level of admiration for Hillary Rodham Clinton on a scale of 1 to 7. The mean rating was 4.06, and the standard deviation was 1.70. (For this exercise, treat this sample as the entire population of interest.) a. Use these ...

statistic
Chebyshev's thereon- the author's generac produces voltage amounts with a mean of 125.0 volts and a standard deviation of 0.3 volt. using chebyshev's theorem,what do we know about the percentage of voltage amounts that are within 3 standard deviations of the mean? What are the...

Statistics
n=1000, bell-shaped Mean - 5,000 ~950 lie +/-100 of 5000 -4900 to 5100 Required 1) Standard Deviation 2) 97.5th percentile value 3) Z-score for 16th percentile

statistics
4. The scores on a university examination are normally distributed with a mean of 62 and a standard deviation of 11. If the bottom 5% of students will fail the examination, what is the lowest score, to the nearest whole number, that a student can have and pass?

Statistics
The weights of adult males are normally distributed with a mean of 172 lb and a standard deviation of 29 lb. 1.Find the weight that divides the upper 2% of weights from the lower 98%. Can anyone please explain how to do this,I have no idea from where to begin. Thanks.

statistics
the distribution of heights of American women aged 18 to 24 is approximately normally distributed with mean 65.5 inche and standard deviation 2.5 inches. what is the probability that a randomly seleted woman is between 60 and 64 inches tall?

Statistics Summary
A bakery has an average daily expense of \$1350. The standard deviation is \$150. The owner takes a sample of 50 bills, what is the probability the mean of his sample will be between \$1200 and \$1500? how do i solve this

statistics
The weights of a group of adult males are normally distributed with a mean of 180lb and standard deviation of 8lb. Find the probability that a randomly chosen male from this group weighs more than 190lb.

Statistics
A shoe store knows that the purchase amount by its customers is a random variable that follows a normal distribution with a mean of \$30 and a standard deviation of \$9. What is the probability that a randomly selected customer will spend \$30 or more at this store?

Statistics
A random sample of 150 towns in a western state had a mean annual precipitation of 2.86 inches. Assume that the population standard deviation is known to be 0.78 inches. Compute the 95% confidence interval for μ.

Statistics/Probability
5) The product is sold in packets whose masses are normally distributes with mean of 1.42 kg and a standard deviation of 0.025 kg. (1) Find the probability that the mass of a packet, selected at random, lies between 1.37 kg and 1.45 kg

Statistics
Carrie attained a score of 650 on the verbal section of her SAT. The mean grade was a 500 with a standard deviation of 100. What percentage of test takers scored below and above Carrie?

statistics/normal distribution
Find the area of the shaded region.The graph to the right depicts IQ scores of Adults (85-120), and those scores are normally distributed with a mean of 100 and a standard deviation of 15

statistics
If the mean value of the weight of a particular brand of dog food is 20.6 lb and the standard deviation is 1.3, assume a normal distribution and calculate the amount of product that falls below the lower specification value of 19.7 lb

Statistics
Suppose that a sample of 50 scores has a mean of Y=90 and the standard deviation is 15. Between what two values of Y will at least 90% of the scores fall? What is the maximun number of scores that can lie out of the interval?

Statistics
The lifetimes of batteries produced by a firm are known to be normally distributed with a mean of 100 hours and a standard deviation of 10 hours. What is the probability a battery will last between 110 and 120 hours?

statistics
The lifetime of a 2 volt non-rechargeable battery has a normal distribution with a mean of 516 hours and a standard deviation of 20 hours. What is the z- score for batteries with lifetimes of 520 hours

statistics
The lifetime of a 2 volt non- rechargeable battery has a normal distribution with a mean of 516 hours and a standard deviation of 20 hours.What is the z- score for batteries with lifetimes of 600 hours

statistics
Waiting times at a doctor office are normally distributed with a mean of 35 minutes, and a standard deviation of 10 minutes. What is the chance a patient would have to wait over 50 minutes?

statistics
A coin mint has a specification that a particular coin has a mean weight of 2.5 g. A sample of 39 coins was collected. Those coins have a mean weight of 2.49491 g and a standard deviation of 0.01372 g. Use a 0.05 significance level to test the claim that this sample is from a ...

statistics
A cell phone service provider has selected a random sample of 20 of its customers in an effort to estimate the mean number of minutes used per day. The results of the sample included a sample mean of 34.5 minutes and a sample standard deviation equal to 11.5 minutes. Based on ...

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

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