Saturday

August 23, 2014

August 23, 2014

Number of results: 7,900

**math**

The time required to finish a test in normally distributed with a mean of 80 minutes and a standard deviation of 15 minutes. What is the probability that a student chosen at random will finish the test in more than 110 minutes?
*May 31, 2011 by chelsa*

**Statistics**

In an advertisement, a shoe store claims that its mean online delivery time is less than 30 hours. A random selection of 36 delivery times has a sample mean of 28.5 hours and a standard deviation of 3.5 hours.
*June 26, 2011 by Eric*

**statistics**

a final exam in statistics has a mean of 73 with a standard deviation of 7.73. Assume that a random sample of 24 students is selected and the mean test score of the sample is computed. What percentage of sample means are less than 70?
*May 11, 2012 by erica*

**stat**

assume that the heights of men are normally distributed with a mean of 68.4 inches and a standard deviation of 2.8 inches.if 64 men are randomly selected, find the probability that they have a mean height greater than 69.4 inches
*June 18, 2012 by veedu*

**statistics**

7) A final exam in Statistics has a mean of 73 with a standard deviation of 7.73. Assume that a random sample of 24 students is selected and the mean test score of the sample is computed. What percentage of sample means are less than 70?
*September 1, 2013 by Anonymous*

**Statistics**

The mean length of the first 20 space shuttle flights was about 7 days with a standard deviation of about 2 days. Using Chebychev's theorem, at least how many of the flights lasted between 3 and 11 days.
*November 16, 2013 by Kenneth*

**Statistics**

In a certain population of clover, the number of flowers on each plant is approximately normally distributed with a mean of 10.8 flowers/plant and a standard deviation of 2.1 flowers/plant. What percentage of the plants fall between 8 and 11 flowers?
*March 8, 2014 by Keisha*

**statistics**

Solve the problem. The lifetime of a new brand of light bulb can be described by a Normal model with a mean of 2000 hours and a standard deviation of 250 hours. Find the percentage of light bulbs that will last more than 2600 hours. A.) 100% B.) 5% C.) 99.18% D.) 0.82% E.) ...
*September 13, 2010 by Anonymous*

**statistics**

A researcher wants to estimate the average time (in minutes) spent in a car daily. This will be done by randomly surveying 300 individuals and calculating the sample mean. Find the probability that the estimate will be in error by less than 5 minutes. Assume that the ...
*June 13, 2011 by Tammy*

**MATH**

Weekly demand for eggs stocked by Waumini grocers is normally distributed. The mean is 500 trays and standard deviation is 100 trays. How many trays should be available for a week if waumini wants to ensure that the probability of running out of stock does not exceed 4%?
*April 5, 2012 by Anonymous*

**statistics**

It is estimated that amounts of money spent on gasoline by customers at their gas stations follows a normal distribution witha standard deviation of $3. It was also found that 10% of all customers spent more than $25. What percentage of customers spent less than $20.
*February 16, 2012 by Anonymous*

**Statistics**

Topic: Normal Probability Distribution Question: Assume that blood pressure readings are normally distributed with a mean if 116 and a standard deviation of 4.8. If the 36 people are randomly selected, How do I find the probability that their blood pressure will be less than ...
*October 16, 2008 by JMN*

**statistics**

a study found that the means waiting time to see a physican at an outpatient clinic was 40 minutes with a standard deviation of 28 minutes. use excel to find each probability. a. what is the probability of more than an hours wait? B. less than 20 minutes? C. at least 10 minutes?
*April 5, 2010 by tina *

**statystics**

A company manufactures wind turbines. A random sample of 25 turbines is taken and the sample mean life is 20.00 years with a standard deviation of 2.50 years. If you were constructing a 90% two-sided confidence interval estimate, the upper limit would be ..
*April 15, 2010 by Anonymous*

**Statistics**

A computer repair service found that a random sample of 45 repair costs had a mean cost of $659. Assume that the population standard deviation is $125. Calculate the margin of error, E, for a 95% confidence interval for the population mean µ.
*December 17, 2012 by Maureen*

**statistics**

ten randomly selected people were asked how long they slept at night. The mean time was 7.1 hours and the (sample) standard deviation was 0.78 hours. Find the 95% confidence interval of the mean time. Assume the variable is normally distributed.
*February 13, 2013 by Asia*

**statistics **

adult males have normally distributed heights with mean of 69.0 in and a standard deviation of 2.8 in. if a clothing manufacture decides to produce goods that exclude the shortest 12% and the tallest 12% of adult males, find the minimum and maximum heights that they will fit.
*April 24, 2013 by kevin*

**stat**

The general population (Population 2) has a mean of 30 and a standard deviation of 5, and the cutoff Z score for significance in a study involving one participant is 1.96. If the raw score obtained by the participant is 45, what decisions should be made about the null and ...
*September 7, 2013 by Jaky*

**Statistics**

As part of studying the relationship between mental and physical health, you obtain the following heart rates: 73 72 67 74 78 84 79 71 76 76 79 81 75 80 78 76 78 In terms of differences in heart rates, interpret these data using the following: (a) the range, (b) the variance, ...
*February 2, 2014 by Tonya*

**probability**

1. The time it takes a student to cycle to school is normally distributed with a mean of 15 minutes and a variance of 2. The student has to be at school at 8.00a.m. At what time should the student leave her house so that she will be late only 4% of the time? 2. In a study for ...
*April 10, 2011 by tan*

**statistics**

Suppose a population distribution of SAT scores has population mean 500 and population standard deviation 100. What is the mean of the sampling distribution of sample means, ybar , calculated from samples of size n = 36
*November 11, 2011 by Emmily*

**maths **

the masses of lettuces sold at a market stall are normally distributed with the mean 600g and standard deviation 20g. 1) find the mass exceeded by 10% of the lettuces. 2) 5% of the lettuces have a mass less than M g. find M
*February 13, 2013 by harish*

**Statistics **

A research worker wishes to estimate the mean of a population by using sufficiently large sample. At the confidence level of 99%,the sample mean will be within 35% of the standard deviation. How large a sample should be taken?
*June 11, 2014 by Brandon*

**Statistics/Probability**

The standard deviation of the masses of articles in a large population is 4.55 kg. Random samples of size 100 are drawn from the population. Find the probability that a sample mean will differ from the population mean by less than 0.8 kg.
*July 17, 2014 by Koylar*

**sTATISTICS**

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?
*August 7, 2014 by KDIZZLE*

**statistics**

4. The average family income in the town of Seneville is $45 000, with a standard deviation of $9000. Assuming that family income is normally distributed, determine the income level below which 80% of the families in this town earn
*August 13, 2014 by Faz*

**math**

Find the z-score for the given raw score, mean, and standard deviation. Assume a normal probability distribution for raw score = Raw score = 66, µ =60 , and ó =6
*July 18, 2010 by Anonymous*

**Statistics**

If student A scored 42 on a test of reading and the test had a mean of 52 and a standard deviation of 8, what percentage of test respondents scored below student A?
*February 13, 2013 by Brittany*

**Statistics**

In a survey, 55% of the voters support a particular referendum. If 30 voters are chosen at random, find the standard deviation of the number of voters who support the referendum.
*October 14, 2013 by Jim*

**statistics**

a researcher is interested in studying people's mean age in a certain region. If the population standard deviation is known to be 8 years and 1.5 year of error margin is allowed, find the minimum simple size the researcher needs to use, knowing that he is going to conduct his ...
*August 23, 2011 by treal*

**statistics**

A researcher is interested in studying people’s mean age in a certain region. If the population standard deviation is known to be 8 years and 1.5 year of error margin is allowed, find the minimum simple size the researcher needs to use, knowing that he is going to conduct his ...
*August 24, 2011 by josh*

**Statistics**

The average hourly wage of employees in a large nationwide industry is $12.96. Assume the variable is normally distributed, with a standard deviation of $4.46. In a randomly selected sample of 10,000 such employees, how many of them (correct to the nearest hundred) would you ...
*November 28, 2011 by Melissa*

**math**

A bond has an average return of 6.8 percent and a standard deviation of 4.6 percent. What range of returns would you expect to see 68 percent of the time? a. 2.2 percent to 11.4 percent b. 4.6 percent to 11.4 percent c. 4.6 percent to 22.8 percent d. 11.4 percent to 22.8 ...
*May 7, 2009 by Emi*

**statistics**

In a particular hospital, newborn babies were delivered yesterday. Here are their weights (in ounces): 106 104 96 123 116 Assuming that these weights constitute an entire population, find the standard deviation of the population. Round your answer to at least two decimal places.
*April 19, 2010 by Nathan*

**math**

a random sample of 42 college graduates who worked during their program revealed that a student spent an averge of 5.5 yeas on the job before being promoted. The sample standard deviation was 1.1 yrs. Using the .99 degree of confidence, what is the confidence interval for the ...
*October 25, 2011 by Dalila*

**Statistics**

A random sample of forty-eight 200 meter swims has a mean of 3:12 minutes and a standard deviation of .09 minute. Construct a 95% confidence interval for the population mean time. I know u: 3.12, sx: .09, n:48, c:.95 What is the formula I use to find the answer? Can anyone ...
*August 1, 2012 by Brian *

**Math/Stats **

I have like 9 more of these problems, can someone please help me out so I can get started. thanx JS In a random sample of 35 tractors, the annual cost of maintenance was $4,425 and the standard deviation was $775. Construct a 90% confidence interval for this. Assume the annual...
*May 1, 2013 by Jessica*

**Math**

The lifetime of a SuperTough AAA battery is normally distributed with mean of 28.5 hours and standard deviation of 5.3 hours. For a battery selected at random, what is the probability that the lifetime will be 25 hours or less? a. 0.7454 b. 0.6604 c. 0.2546 d. 0.3396
*August 7, 2011 by Justina*

**Statistics**

The lifetime of a certain smart phone battery has an unknown distribution with mean value of 8 hours and standard deviation of 2 hours. What is the approximate probability that the average battery lifetime of a sample of 36 batteries will exceed 8.1 hours?
*December 12, 2011 by jacob*

**Statistics**

The lifetime of a certain smart phone battery has an unknown distribution with mean value of 8 hours and standard deviation of 2 hours. What is the approximate probability that the average battery lifetime of a sample of 36 batteries will exceed 8.1 hours?
*December 12, 2011 by jacob*

**Statistic**

IQs among undergraduates at Mountain Tech are approximately normally distributed. The mean undergraduate IQ is 110. About 95% of undergraduates have IQs between 100 and 120. The standard deviation of these IQs is about A. 5 B. 10 C. 15 D. 20 E. 25
*March 4, 2013 by Mm*

**math**

Following are the lengths in yards of the nine holes of the University Golf Course: 480,460,450,380,360,350,330,180,160 Find each of the following measures with respect to the lengths of the holes: d. Standard deviation 36.07263
*June 16, 2009 by is this right!!!*

**stats**

To test the hypothesis H0 : ě = 100 against H1 : ě > 100, a statistics practioner randomly sampled T observations and found the mean x = 106 and the standard deviation sx = 35. The value of the test statistic is equal to (1) 1.1743 (2) −1.7143 (3) 0.1714 (4) 17.143 (5...
*March 31, 2010 by sam*

**Statistics**

Given the following set of numbers: x=7.1, 1.8, 2.1, 1.5, 2.1. Find the median, mean and standard deviation. State the formulas (or procedure) for these values, plug the numbers into the formula and evaluate the results. Compare the mean and median. Which is more resistant to ...
*November 18, 2010 by Maryan*

**math**

A gallup poll of 1236 adults showed that 14% believe that bad luck follows if your path is crossed by a black cat, so n=1236 and p=0.14 1.Find the mean? 2.Find the standard deviation? 3.Find the ND (np > 5 and nq > 5 ?) 4.Find the min, max of usual values by RROT
*September 28, 2011 by marie*

**statistics**

A math professor notices that scores from a recent exam are normally distributed with a mean of 64 and a standard deviation of 5. Answer the following questions using integer values. What score do 75% of the students exam scores fall below? And, how was this answer calculated?
*February 14, 2012 by Dora*

**statistics**

A telephone company representative estimates that 40% of its customers use voice mail. To test this hypothesis, she selected a sample of 100 customers and found that 37 used voice mail. At a standard deviation of 0.01, is there enough evidence to show the proportion differs ...
*July 19, 2012 by Kay*

**statistics**

a pizza shop owner wishes to find the 95% confidence interval of the true mean cost of a large plain pizza. how large should the sample be if she wishes to be accurate to within $0.15? a previous study showed that the standard deviation of the price was $0.26
*March 17, 2013 by paula*

**Statistics**

Reginald Brown an inspector from the department of weights and measures, weighs 15 eighteen-ounce cereal boxes of corn flakes. he finds their mean weight to be 17.78 ounces with a standard deviation of .4 ounces. are the cereal boxes lighter than they should be? let Alpha = .01
*May 4, 2014 by Mark*

**Stats**

A researcher wants to estimate the mean serum cholesterol level for college age women. In a past study the standard deviation for this measure was 42 units. of the researcher wants to be off in his estimate by no more than three units (with 99% confidence) how large must his ...
*May 9, 2014 by Frabkie*

**Math**

Suppose a large number of people take a take and every single student gets half of the answers correct. In this case, the standard deviation is: A) Equal to the mean B) Equal to the median C) Equal to zero D) Impossible to determine without more information
*September 17, 2007 by John*

**Statistics**

Suppose an automobile association reports that the average time it takes to respond to an emergency call is 25 minutes. Assume the variable is approximately normally distributed and the standard deviation is 4.5 minutes. If 104 calls are randomly selected, approximately how ...
*February 3, 2012 by Renita*

**math**

A traffic engineer plans to estimate the average number of cars that pass through an intersection each day. Based on previous studies the standard deviation is believed to be 52 cars. She wants to estimate the mean to within ± 10 cars with 90 percent confidence. The needed ...
*February 28, 2012 by Yo*

**Statistics**

The average age of vehicles registered in the united states is 96 months, with a standard deviation of 16 months. If a random sample of 36 vehicles is selected, find the probability that the mean of their ages is between 90 and 100 months. Provide four places past the decimal ...
*March 4, 2012 by Darren*

**Statistics Please Help**

One reason for standardizing random variables is to measure variables with: A. dissimilar means and similar standard deviations in like terms B. different means and standard deviations on a non-standard scale C. similar means and standard deviations on two scales D. different ...
*May 26, 2013 by Austin *

**Math**

In a set of 400 ACT scores where the mean is 22 and the standard deviation is 4.5, how many scores are expected to be lower than 26.5? How many of the 400 scores are expected to be greater than 31?
*March 3, 2013 by Sarah*

**statistics**

Group the largest data set and find mean, median, mode, variance, standard deviation, 15-th, 45-th and 80-th percentiles of the grouped data. Then find the same sample statistics using the ungrouped data. Is there any difference? Comment.
*November 20, 2011 by metu*

**Statistics homework distribution problem? **

i need help with how to solve this: consider a normal distribution with mean 30 and standard deviation 2. what is the probability a value selected at random from this distribution is greater than 30? the book gives me the answer but i need to know how to solve it. please help?
*February 20, 2012 by jess*

**statistics**

The average salary for graduates entering the actuarial field is $40,000. If the salaries are normally distributed with a standard deviation of $5000 (σ = 5000), find the probability that a graduate will have a salary over $45,000: P(X > 45,000).
*March 7, 2012 by Mary*

**statistics**

Participants from the National Health and Nutrition Examination Survey, 2003–2004, had a mean BMI of 28.3 with a standard deviation of 6.0. Assuming BMI is normally distributed, what proportion of the participants had a BMI measure over 35?
*May 7, 2013 by ali awan*

**statistics**

The weight of a can made from a machine is normally distributed with a mean of 25 grams and a standard deviation of 0.4 grams. What percentage of the cans from this machine would not meet the minimum required weight of 24 grams? Round to the nearest hundredth of a percent
*November 5, 2013 by lynda*

**math**

The weight of a can made from a machine is normally distributed with a mean of 25 grams and a standard deviation of 0.4 grams. What percentage of the cans from this machine would not meet the minimum required weight of 24 grams? Round to the nearest hundredth of a percent
*November 5, 2013 by lynda*

**chemsitry **

You have been provided 100mL of a 1000ug/ml barium standard what volume of this standard must be diluted into 50mL of ID water to produce a 30 ug/ml standard ? if you given a full 100mL of the same standard provied calculate the amount of standard and final volume required to ...
*January 31, 2010 by Samah *

**Statistics**

Males make a mean of 531 on math SAT with standard deviation of 114. Minimum 600 score. what's the % of males that don't satisfy this requirement? Pregnancies usually distributed mean of 268 days and standard distribution 15 days. Baby born three week premature at least 3 ...
*December 5, 2006 by Sue*

**statistics**

4. Are women getting taller? In one state, the average height of a woman aged 20 years or older is 63.7 inches in 1990. A random sample of 100 women is taken to test if women’s mean height today is different from 1990. The mean height of the 100 surveyed women is 63.9 inches. ...
*December 16, 2013 by Amanda*

**statistics**

For a specific truck traveling at 50 miles per hou… ... normally distributed with a mean of 120 feet and a standard deviation of 12 feet. ... into the path of the truck and stops at a distance of 150 feet from the truck. ... to a complete stop, what is the probability that ...
*February 4, 2011 by miky*

**Stats**

A random sample of 30 women drank an average of 15 cups of coffee per week during examination finals, with the sample standard deviation equal to 3 cups. A upper limit of an approximate confidence interval with 95% of the population average cup drunk is ?
*March 30, 2010 by Mariaan*

**Statistics**

For a normal distribution with a mean of m = 80 and a standard deviation of s = 20, find the proportion of the population corresponding to each of the following scores. a. Scores greater than 85 b. Scores less than 100 c. Scores between 70 and 90 I believe this is the correct ...
*July 26, 2010 by Lyndon*

**statistic**

To learn more about the size of withdrawals at a banking machine, the proprietor took a sample of 75 withdrawals and recorded the amounts. Determine the mean and standard deviation of these data, and describe what these two Statistics tell you about the withdrawal amounts. ...
*January 31, 2011 by qui*

**statistics**

What is wrong with the following statements? a) For a large n, the distribution of observed values will be approximately Normal b) 68-95-99.7 rule says that "x bar" should be within m (mean) +/- 2 SD (standard deviation) about 95% of the time c) The central limit theorem ...
*October 14, 2012 by ami*

**statistics**

A researcher is interested in estimating the average salary of teachers in a large urban school district. She wants to be 95% confident that her estimate is correct. If the standard deviation is $1050 (σ = 1050), how large of a sample is needed to be accurate within $200...
*October 29, 2012 by jr*

**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 ...
*January 4, 2013 by Alia*

**statistics**

Computer Services wants to estimate the mean number of hours college students use on campus computers each day. They want to be within .1 hour of the true value with 99% confidence. From a previous study, the standard deviation is assumed to be .6 hour. What size sample is ...
*December 11, 2010 by John Davis*

**statistics**

A group of 200 students takes the Kaplan course in hopes that it will improve their SAT scores above the national mean of 500 on the math section. The population standard deviation of the SAT is known to be 100. Use an alpha level of .05 when answering the following questions...
*October 16, 2012 by sarah*

**statistics**

In a study designed to test the effectiveness of magnets for treating back pain, 40 patients were given a treatment with magnets and also a sham treatment without magnets. Pain was measured using a scale from 0 to 100. After given the magnet treatments, the 40 patients had ...
*November 19, 2013 by Sharie*

**Math**

A carnival game consists of rolling a single fair die, with the following results: you win $8 for a 6, $7 for a 5, and lose $3 for any other number. Set a probability distribution, and calculate (already did) the Expected value = .50 Variance= 24.58 standard deviation= 4.96 ...
*December 13, 2007 by Anastasia*

**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 6 hours, what is the required sample size if the error is to be less than ˝ hour with a ...
*December 8, 2008 by Zenna*

**math **

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...
*April 4, 2011 by tom*

**math **

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...
*April 4, 2011 by ibrahim *

**i need help!!!**

probability and statistics a z score is z = x - xbar divided by s which is standard deviation s = 6.36 x = ? xbar = 54.8 the x is all the data sub. from 54.8 individually which i came up with 1.2 and divided it by 6.36 and the number is .1886.....and the answer in the back of ...
*September 10, 2008 by emily*

**Statistics**

You are a buyer bidding on a lot of 10,000 uncut diamonds. You select 100 stones at random, sight unseen, from the lot. The average weight is 0.98 ct with a standard deviation in the sample of 0.11 ct. What is the 95% confidence interval for the average weight of a stone in ...
*March 4, 2010 by Fran*

**statistics**

Distance travelled in a week by sales staff employed by nationwide security firm is approximately normally distributed with a mean of miles and standard deviation of 48 miles. Estimate the percentage of staff who in a week travel less than 80 miles
*May 3, 2010 by Anonymous*

**statistics**

For every 100 births in the U.S., the number of boys follows, approxiamately, a normal curve with a mean of 51 and standard deviation of 5 boys. If the next 100 births in your local hospital resulted in 36 boys (and thus 64 girls) would that be unusual?
*April 5, 2011 by Anonymous*

**Statistics**

1. The sociologist surveyed the households in a small town. The random variable X represents the number of dependent children in the households. The following is the probability distribution of X: X 0 1 2 3 4 P(X) 0.07 0.20 0.38 k 0.13 (a) Find the missing probability value of...
*June 1, 2011 by LadyJustice85*

**Statistics**

The distribution of heights of adult males has a mean of 69 inches and a standard deviation of 4 inches. A random sample of 36 adult males is selected. Find the probability that the average height will be more than 70 inches. a.0.668 b.0.858 c.0.908 d.0.995
*October 31, 2011 by Monique*

**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?
*April 16, 2012 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?
*May 7, 2013 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.
*April 4, 2014 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!
*December 4, 2012 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?
*March 8, 2011 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?
*November 4, 2012 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
*December 1, 2012 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?
*March 18, 2013 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?
*March 18, 2013 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 ...
*August 21, 2008 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.
*May 25, 2011 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?
*March 6, 2012 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
*March 10, 2012 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
*August 4, 2012 by AMbe*

**Math**

Assume a data set is normally distributed with mean 11 and standard deviation 3. If the data set contains 30 data values, approximately how many of the data values will fall within the range 8 to 14?
*July 12, 2014 by Shelagh*

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