# Standard Deviation

10,100 results

**Prob. & Statistics**

If one event, say Black, has P(.70) and another event, say Red, has P(.30). What is the probability in ten events of alternating choices, Red then Black, and being 100% correct, 90% correct. What should be the expected % correct and what is the standard deviation?

**Excel formula help**

Formula to multiply the number in cell 4k times standard deviation of the numbers in cell z2 through z10 I don't understand cell z2 through z10 I have never had excel (4kxz2xz10) Please write this correctly

**statistics**

mean = 60 wpm standard deviation= 15 wpm a.What is the probability that a randomly selected typist's net rate is at most 60 wpm? less than 60 wpm? b. What is the probability that a randomly selected is between 45 and 90 wpm?

**statistics**

The value of the z-score that is obtained for a hypothesis test is influenced by several factors. Some factors influence the size of the numerator of the z-score and other factors influence the size of the standard error in the denominator. For each of the following indicate ...

**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...

**statistics**

Help!!!!!! A confidence interval estimate for the population mean is given to be (39,90, 48.11) If the standard deviation is 11.473 and the sample size is 52 determine the maximum error of the estimate. determine the confidence level used for the given confidence interval

**statistics**

The number of vacation days taken by employees of a company is normally distributed with a mean of 14 days and a standard deviation of 3 days. For the next employee, what is the probability that the number of days of vacation taken is less than 10 days? More than 21 days?

**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

**statistics**

The number of vacation days taken by employees of a company is normally distributed with a mean of 14 days and a standard deviation of 3 days. For the next employee, what is the probability that the number of days of vacation taken is less than 10 days? More than 21 days?

**Statistics**

Use a chi-squared test to test the claim about the population variance or standard deviation at the given level of significance and using the given sample statistics. Claim: ơ2 ≤ 60; α = 0.025. Sample statistics: s2 = 72.7, n = 15

**AP Stats (math)**

A large metropolitan area found that the time it takes for people to commute to work has a mean of 20.5 minutes and a standard deviation of 15.4 minutes. What is the probability that a random sample of 40 people have a mean commute time greater than 25 minutes?

**Math**

If light bulbs have lives that are normally distributed with a mean of 2500 hours and a standard deviation of 500 hours, approximately what percentage of light bulbs has a life of more than 3000 hours? A. About 84% B. About 68% C. About 32% D. About 16% Answer B

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

If light bulbs have lives that are normally distributed with a mean of 2500 hours and a standard deviation of 500 hours, approximately what percentage of light bulbs has a life of more than 3000 hours? A. About 84% B. About 68% C. About 32% D. About 16% Answer B

**math**

A tractor manufacturing company machines axles to extremely small tolerances. The main power axles have a mean diameter of 3.0000 inches and a standard deviation of 0.0050 inch. What is the probability that a given axle will have a diameter between 2.9915 and 3.0004 inches? ...

**Statistics**

A battery manufacturer is positive that its AA batteries last for 1,000 hours. However, you’re working for Consumer Reports and you don’t agree with what they say about their product. So, you buy 400 batteries and you test them out. Your findings are that the batteries ...

**Math**

For a binomial distribution with n=20 trials and probability of success p=.05, we let r= number of successes out of 20 trials. Use the normal approximation to estimate P(6<=r<=12). How does this value compare with the corresponding probability obtained using the binomial...

**math- study question for final**

You are given a sample of 106 body temperatures having a mean of 98.2 F and a standard deviation of 0.62 F. You are asked to test the hypothesis that the population mean body temperature is 98.6 F using a 0.05 significance level. What value should you use for the test ...

**statistics**

What is the difference between the height of the tallest man at 92.95" and the mean height of me at 69.6" and a stanard deviation of 2.8? How many standard deviations is that? Convert tallest man to a z score Does tall mans height meet the criterion of being unusual by ...

**statistics**

30 new babies were born yesterday in the hospital. If the average weight of a new born is 7.5 pounds with a standard deviation of 2.1 pounds, what is the probability of the average weight for these 30 newborns is between 7.2 and 7.6 pounds. Remember, all probabilities are ...

**math**

The mean score on a Math exam was 50% and the standard deviation was 10%. Assume the results were normally distributed. (a) What percent of students earned a score between 50% and 70%? (b) If 60 students took the exam, how many got a score between 50% and 70%?

**AP Stats**

The mean weight of pears grown in a certain orchard is 6 ounces with a standard deviation of .5 ounces. A random sample of 30 pears is selected. What is the approximate probability that the sample mean weight is less than 5.5 ounces?

**math**

If light bulbs have lives that are normally distributed with a mean of 2500 hours and a standard deviation of 500 hours, what percentage of light bulbs have a life less than 2500 hours?

**statistics**

If light bulbs have lives that are normally distributed with a mean of 2500 hours and a standard deviation of 500 hours, what percentage of light bulbs have a life less than 2500 hours?

**Statistics**

If light bulbs have lives that are normally distributed with a mean of 2500 hours and a standard deviation of 500 hours, what percentage of light bulbs have a life less than 2500 hours

**MATH 2**

It is found that the number of raisins in a box of a popular cereal is normally distributed, with a mean of 133 raisins per box and a standard deviation of 10 raisins. My cereal box has 147 raisins. What is the z-score for this box of cereal?

**MATH**

it is found that the number of raisins in a box of a popular cereal is normally distrubuted, with a mean of 133 raisins per box and a standard deviation of 10 raisins. my cereal box has 152 raisins, what is the z-score for this box of cereal?

**Statistics**

The heights of 18-year-old men are approximately normally distributed with mean 68 inches and standard deviation 3 inches. What is the probability that the average height of a sample of ten 18-year-old men will be less than 70 inches? Round your answer to four decimal places. ...

**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 ...

**math**

if, instead of assuming that the mean body temperature is 98.20 degree Ferinheight, we assume that the mean is 98.60 F(as many people believe), wht is the chance of randomly selecting 106 people and getting a mean of 98.20 degree F or lower? (continue to assume that the ...

**Statistics**

A manufacturer of a low-tar cigarette claims that their cigarettes contain an average of 16.3 mg of tar with a standard deviation of 3.1 mg per cigarette. How many sample cigarettes must the manufacturer observe to be 99% confident that the width of the confidence interval is ...

**algebra homework check**

The monthly rents for the apartments in a Business building are listed below. $425, $550, $550, $550, $650, $650, $650, $650, $800, $900 Part A: Find the mean$637.50 median=$650 mode=$650 range=$475 and standard deviation of the rents???

**Management**

The bulbs manufactured by a company gave a mean life of 3000 hours with standard deviation of 400 hours. If a bulb is selected at random, what is the probability it will have a mean life less than 2000 hours? Question: 1) Calculate the probability. 2) In what situation does ...

**fnu**

The average age of doctors in a certain hospital is 50.0 years old. Suppose the distribution of ages is normal and has a standard deviation of 4.0 years. If 16 doctors are chosen at random for a committee, find the probability that the average age of those doctors is less than...

**statistics**

The average age of doctors in certain hospital is 43 years old. Suppose distribution of ages is normal and the standard deviation is 8.0 years. If 25 doctors is chosen at random for a committee, find the probability the average age for those doctors is less than 43.8 years. ...

**statistics**

we want to if men and women perform differently on statistics tests. The average of 15 men's scores was 76. The average of 10 women's scores was 83. The standard deviation in both cases is 10. Test at 5% significance level. what is the null and alternate hypothese? is it a one...

**statistics**

A charity believes that when it puts out an appeal for charitable donations the donations it receives will normally distributed with a mean of $50 and standard deviation of $6, and it is assumed that donations will be independent of each other. (i) Find the probability that a ...

**statistics**

calculate the correlation for data set A. Data Set A: xi = 65, 55, 50, 45, 35 yi= 44, 52, 68, 20, 36 I know how to find the mean, variance, standard deviation, and z-score. The part I am having trouble finding is the ZxiZyi. In the chart that I have to fill in it says Zxi in ...

**Stats....how do i do this??**

SAT I scores around the nation tend to have a mean scale score around 500, a standard deviation of about 100 points, and are approximately normally distributed. What SAT I score within the population would have a percentile rank of approximately 16? Im not sure how to do this...

**statistics**

Assume that women's heights are normally distributed with a mean=63.6 in. and standard deviation = 2.5 in. a) To be eligible for the US Marine Corps, a woman must have a height between 58 in. and 73 in. Find the percentage of women who satisfy that requirement. b)If the ...

**Algebra 2**

Times for an ambulance to respond to a medical emergency in a certain town are normally distributed with a mean of 450 seconds and a standard deviation of 50 seconds. Suppose there are 160 emergencies in that town. In about how many emergencies are the response times expected ...

**Statistics**

Second Problem A. determine the mean, median, and the standard deviation B. Determine the coefficient of skewness using Pearson's method C. Determine the coefficient of skewness using the software method Commison earned($000)last year by the sales representatives at the ...

**Math**

What is the difference between the height of the tallest man at 92.95" and the mean height of men at 69.6" and a stanard deviation of 2.8? How many standard deviations is that? Convert tallest man to a z score Does tall mans height meet the criterion of being unusual by ...

**statistics**

Boxes of bran flakes are known to be normally distributed with a mean weight of 475g and a standard deviation of 10g.Calculate the probability of a box having a weight exceeding 485 grams. Calculate the probability that the mean weight of sixteen boxes will exceed 480g.

**statistics**

the weights of shells follow a normal distribution. a random sample of 12 hybrid shells a a mean weight of 1.7 pounds with standard deviation 0.24 pounds. Find a 95 % confidence interval level for the mean weight if the fall catch is within 0.1 pounds of the sample estimate

**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 rime will be a. Between 25 and 30 minutes? b. less than 35 ...

**statistics for health research**

the income of a group of 10,000 health system employees was found to be normally distributed with a mean=750 pm and standard deviation=50. show that of this group about 95% had income exceeding 668 and only 5% had income exceeding 832

**Statistic**

A random sample of size 20 drawn from a normal distribution has a sample mean of 8 and a sample standard deviation of 4. A) Compute the sample test statistic t under the null hypothesis H_0: Mue(mean)=7 B) State the alternate hypothesis if you believe that the population mean ...

**statistics**

The physical plant at the main campus of a large state university receives daily requests to replace florecent lightbulbs. The distribution of the number of daily requests is bell-shaped and has a mean of 37 and a standard deviation of 3. Using the empirical rule (as presented...

**stats**

Scores on a test are approximately normally distributed with a mean of 70 and a standard deviation of 9. The teacher wants to give A’s to the top 10% of students, B’s to the next 25%, and C’s to the next 42%. a.) what is the bottom cutoff for a C grade? b.) what is the ...

**Bio**

im stuck on these questions for my study guide Please help! i don't want links. thanks 1. Which of the follwoing would be an appropriate measure of the phenotypic variation of a trait in a population? a) the mean of the trait in the population b) the standard deviation of the ...

**statistics**

Assume the population distribution of FEV is normal with standard deviation 400 mLi. (a) find P(E) is n=15 and population mean is 2800 mLi (B) find P(E) is n=15 and the population mean is 2600mLi (C) How does P(E) depend on the population mean?

**statistics**

Among coffee drinkers, men drink a mean of 2.8 cups per day with a standard deviation of 0.5 cups. Assume the number of drinking per day follows a normal distribution. What proportion drink 3 cups per day or more?

**statitics**

Certain data includes 36 body temperatures for which the sample mean is equal to 98.20 °F and standard deviation of 0.62 °F. Using this sample statistics, construct a 95% confidence interval of the mean body temperature. What does the sample suggest about the use of 98.6°F ...

**math**

No idea how to do this. I looked in my book and there usually is a data set present to get the first, second and third quartile. The lifetimes of lightbulbs of a particular type are normally distributed with a mean of 392 hours and a standard deviation of 9 hours. Find the ...

**homework statistics**

Consider a random sample with sample mean x. If the sample size increased from n = 40 to n = 360, then the standard deviation of x will: a. remain the same b. increase by a factor of 9 (will be multiplied by 9) c. decrease by a factor of 9 (will be multiplied by 1/9) d. ...

**statistics**

Someone who has never seen a normal die before decides to estimate the mean value of all its faces (μ) by rolling it many times. First, they are told that the standard deviation is σ = 1.7. Then, they roll the die 50 times and get a sample mean of x-bar = 3.7. ...

**statistics probability**

Alice earned a score of 940 on an IQ test.The mean test score was 850 with a standard deviation of 100.(Assume that test scores are normally distributed). Q1a).What proportion of students had a higher score than alice? Qb)Find the score exceeded by 2.5% of the students.

**Stats**

Consider the following Hypotheses test: Ho:m>=80 Ha:m<80 A sample of 121 provided a sample mean of 77.3. The population Standard Deviation is known to be 16.5. A. compute the value of test statistic B. Determin the p value: and at 93.7% confidence, Test the above ...

**statistics**

A vending machine is designed to dispense a mean of 7.6 oz of coffee into an 8-oz cup. If the standard deviation of the amount of coffee dispensed is 0.4 oz and the amount is normally distributed, find the percent of times the machine will a) dispense less than 7.0 oz. b) ...

**Statistics**

A random sample of 50 students chosen from an elementary school with 400 students was found to have a mean allowance of $26 per week with a standard deviation of $8. Obtain a 98% confidence interval for the total amount of allowance money given to students in this school per ...

**Statistics**

The distribution of a sample of the outside diameters of PVC gas pipes approximates a symmetrical, bell-shaped distribution. The arithmetic mean is 11.0 inches, and the standard deviation is 2.0 inches. About 68 percent of the outside diameters lie between what two amounts? 8....

**Algebra 2**

A simple random sample of 50 adults was surveyed, and it was found that the mean amount of time that they spend surfing the Internet per day is 54.2 minutes, with a standard deviation of 14.0 minutes. What is the 99% confidence interval for the number of minutes that an adult ...

**statistics**

A new national survey found that Americans drink an average of 6 glasses of water daily, instead of the recommended 8. Assuming that the number of glasses of water is approximately normally distributed with a standard deviation of 1.7 glasses, what proportion of Americans ...

**computers**

Although label choices vary for different printers, your textbook recommends __________ for laser and ink jet printers. A. Avery standard, 5160, Address B. Avery standard, 6150, Label C. Avery standard, 6150, Address D. Avery standard, 5160, Label I've looked through the book ...

**stats**

A random sample of 40 men drank an average of 20 cups of coffee per week during examination final, with the population standard deviation equal to 6 cups. A lower limit of an approximate 95% confidence interval the population average cup of coffee is (1) 20.000 (2) 21.859 (3) ...

**Math: i do not understand**

A tractor manufacturing company machines axles to extremely small tolerances. The main power axles have a mean diameter of 3.0000 inches and a standard deviation of 0.0050 inch. What is the probability that a given axle will have a diameter between 2.9915 and 3.0004 inches? ...

**ap stats**

based on over 800 housing prices collected at random from the city of Los Angeles, an investigator constructed a histogram and found that the distribution of housing prices was heavily skewed to the right. Which of the following statistics will best represent the center of ...

**Statistics**

Cellular Phone Sales The probability that a cellular phone company kiosk sells X number of new phone contracts per day is shown below. Find the mean, variance, and standard deviation for this probability distribution. X 4 5 6 8 10 P (X) 0.4 0.3 0.1 0.15 0.05 What is the ...

**math PLEASE URGENT**

if normal blood cholestrol level is 5.8 mM and a treatment caused a drop of 1.0 mM with a standard deviation of the difference of 2.0 mM what is the minimum number of individuals that should be used in the drug trial to determine whether or not it is effective i know you have ...

**Statistics**

Thomas economic forecasting, Inc. and Harmon econometrics have the same mean error in forecasting the stock market over the last ten years. However, the standard deviation for Thomas is 30 points and 60 points for harmon.At the .05 signifcance level can we conclude that there ...

**statistics**

Given that x is a normally distributed random variable with a mean of 60 and a standard deviation of 10, find the P(56 < x <74). Please show all your work and write your answer in a complete sentence. Using the information from question 1, what percentage of the ...

**stats homework **

the monthly demand for a certain product is a normal random variable with a mean of 50 and standard deviation 10 a) if you have 60 units on a stock at the beginning of the month, what is the probability you will still have stock remaining at the end of the month? b)what is the...

**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? 71 100 237 199 164 269 193 379 252 233 388...

**Finance**

Use the following information to calculate the covariance of asset A with an equally weighted portfolio of assets B and C. Asset Standard Deviation A 20% B 30% C 40% The correlation coefficient between A and B is 0.6. The correlation coefficient between A and C is 0.5. The ...

**Math-Answer included**

{9, 7, 13, 24, 32, 45, 47} First you have to find the mean The mean is 9+7+13+24+32+45+47=177/7=25.2857=25.29 Find the standard deviation for the given data. Round your answer to one more decimal place than the original data. {9, 7, 13, 24, 32, 45, 47} (25.29-9)^2=16.29^2=265....

**Math**

A consumer buys n light bulbs, each of which has a lifetime that has a mean of 800 hours, a standard deviation of 100 hours, and a normal distribution. A light bulb is replaced by another as soon as it burns out. Assuming independence of the lifetimes, find the smallest n so ...

**Math**

A consumer buys n light bulbs, each of which has a lifetime that has a mean of 800 hours, a standard deviation of 100 hours, and a normal distribution. A light bulb is replaced by another as soon as it burns out. Assuming independence of the lifetimes, find the smallest n so ...

**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? Label and ...

**statistics**

A state administered standardized reading exam is given to eighth grade students. The scores on this exam for all students statewide have a normal distribution with a mean of 506 and a standard deviation of 69. A local Junior High principal has decided to give an award to any ...

**Business Statistics**

A filling machine is designed to fill soda bottles with 16 ounces of soda. The distribution for the weight of the bottles is normal. Twenty bottles are selected and weighed. The sample mean is 15.3 ounces and sample standard deviation is 1.5 ounces. Develop a 90% confidence ...

**P-Chem**

The equilibrium constant K for the hydrolysis of adenosine triphosphate (ATP) to adenosine diphosphate (ADP) and phosphate is 1.66X10^5 at 37 degrees celcius, and Standard Delta H is -20.1 kJ/mol. Calculate Standard Delta S for the hydrolysis at 37 degrees celcius. On the ...

**statistics**

If we know that the length of time it takes an MBA student to find a parking spot near the DePaul Center follows a normal distribution with a mean of 3.5 minutes and a standard deviation of 1 minute, find the point in the distribution that 75.8% of the MBA students exceed when...

**math**

Assume that the average annual salary for a worker in the United States is $30,500 and that the annual salaries for Americans are normally distributed with a standard deviation equal to $6,250. Find the following: (A) What percentage of Americans earn below $19,000? (B) What ...

**Math**

Assume that the average annual salary for a worker in the United States is $30,500 and that the annual salaries for Americans are normally distributed with a standard deviation equal to $6,250. Find the following: (A) What percentage of Americans earn below $19,000? (B) What ...

**Statistics**

The Amount of filling a half-liter (500ml)soft drink bottle is normally distributed. The process has a standard deviation of 5ml. The mean is adjustable. A. Where should the mean be set to ensure a 95% probability that a half-liter bottle will not be under filled? B. A 99% ...

**Math/Probability/Statistics**

Find the expected value and the standard deviation in the following raffle: Value Tickets Grand Prize: $2,000.00 1 Second Place Prize: $800.00 20 Third Place Prize: $40.00 60 Fourth Place Prize: $30.00 300 Total Number of Tickets Sold: 10000

**algebra 2b**

A simple random sample of 50 adults was surveyed, and it was found that the mean amount of time that they spend surfing the Internet per day is 54.2 minutes, with a standard deviation of 14.0 minutes. What is the 99% confidence interval (z-score = 2.58) for the number of ...

**Statistics**

is the standard deviation a measure of the center or distribution... my teacher told me center i read the article and i\'ve been lead to believe its a measure of the distribution not the center... if it is a measure of the center how is it? I think it\'s a measure of the ...

**Stats**

National Packing Materials Company claims its X20 box can hold loads up to at least 80 pounds. Smith Widget Company has been using the boxes for one year and feels the boxes fail at lighter loads. Hearing the complaints from Smith, the lead engineer for National Packaging ...

**Statistics**

A purchasing agent for a trucking company is shopping for replacement tires for their trucks from two suppliers. The suppliers' prices are the same. However, Supplier A's tires have an average life of 60,000 miles with a standard deviation of 10,000 miles. Supplier B's tires ...

**Statistics**

A purchasing agent for a trucking company is shopping for replacement tires for their trucks from two suppliers. The suppliers' prices are the same. However, Supplier A's tires have an average life of 60,000 miles with a standard deviation of 10,000 miles. Supplier B's tires ...

**Statistics**

1. A simple random sample of FICO credit rating scores is listed below: 714 751 664 789 818 779 698 836 753 834 693 802 a. Find range, variance, and standard deviation. b. As of this writing, the mean FICO score was reported to be 678. Based on these results, is a FICO score ...

**algebra**

Three firms carry inventories that differ in size. Firm A's inventory contains 2000 items, firm B's inventory contains 5000 items, and firm C's inventory contains 10,000 items. The population standard deviation for the cost of the items in each firm's inventory is = 144. A ...

**statistics**

drug company promises to help people lose at least 3 pounds per week. 15 people use the drug. they lose an average of 2.8 lbs per week with a standard deviation of .5lbs. is this a left tail or right tail and why?

**Statistics**

Please can some one help me with the following: A fisherman finds that approximately 17% of all his fish go bad by the time he takes them to the market. The fisherman catches 1,000 fish. A. How many will go bad by the time he takes them to the market? B. Find the standard ...

**Statistics**

Please can some one help me with the following: A fisherman finds that approximately 17% of all his fish go bad by the time he takes them to the market. The fisherman catches 1,000 fish. A. How many will go bad by the time he takes them to the market? B. Find the standard ...

**Statistics**

32% of adult internet users have purchased products or services online. For a random sampling of 200 adult users, find the mean, variance and standard deviation for the number who have purchased goods or services online?

**statistics**

a random sample of 80 college students was selected to participate in a experiment. the mean of the sample is 317 points, the standard deviation of 37 there are 310 students that didn't complete the experiment 1. compute the appropriate test statistic? 2. what is the critical ...

**statistics**

SAT I scores around the nation tend to have a mean scale score around 500, a standard deviation of about 100 points, and are approximately normally distributed. What SAT I score within the population would have a percentile rank of approximately 97.5? Show all work as to how ...

**Statistics**

Scores on a visual perception test are normally distributed with a mean of 2020 and a standard deviation of 250. a)If one subject is randomly selected and tested, find the probability of a score greater than 1800 b)if 50 subjects are randomly selected and tested fid the ...