Friday

September 4, 2015
Number of results: 19,945

**statistics**

The tread life a certain brand of tires is known to be normally distributed with a mean of 60,000 miles and a standard deviation of 5,000 miles. The company wishes to set the warranty so that only 4% of the tires will need to be replaced. What should the warranty mileage be?
*October 29, 2014 by Wendy*

**statistics**

The tread life a certain brand of tires is known to be normally distributed with a mean of 60,000 miles and a standard deviation of 5,000 miles. The company wishes to set the warranty so that only 4% of the tires will need to be replaced. What should the warranty mileage be?
*October 30, 2014 by Anonymous*

**statistics**

It is claimed that an automobile is driven on the average more than 20,000 kilometers per year. Random sample of 10 automobile owners are asked to keep a record of the kilometers they travel. If the sample mean and standard deviation of automobile driven are found to be 23,500...
*June 3, 2011 by Ali*

**prob and stats**

The tread lives of the Super Titan radial tires under normal driving conditions are normally distributed with a mean of 34000 mi and a standard deviation of 1700 mi. (a) What is the probability that a tire selected at random will have a tread life of more than 35071 mi? Round ...
*October 15, 2010 by br0Ok3*

**statistics**

A survey found that women's heights are normally distributed with mean 63.5 in. and standard deviation 2.3 in. The survey also found that men's heights are normally distributed with a mean 68.7 in. and a standard deviation 2.8. (a) Most of the live characters at an amusement ...
*December 13, 2014 by Kelli*

**math**

a tire manufacturer believes that the tread life of its tires are normally distributed and will lst an average of 60,000 miles with a standard deviation of 3,000 miles. sixty-four randomly selected tires were tested and the average miles where the tire failed were recorded. ...
*May 31, 2011 by monk*

**Statistics**

find the 90% confidence interval for the variance and standard deviation of a sample of 16 and a standard deviation of 2.1 Assume the variable is normally distributed.
*October 24, 2010 by Anon*

**statistics**

A construction zone on Kings Road has a posted speed of 45 kilometers per hour. The speeds of vehicle passing through this construction zone are normally distributed with a mean of 46 kilometers per hour and a standard deviation of 4 kilometers per hour. Find the percentage ...
*May 11, 2012 by Nesa*

**Statistics **

9 points) In a normally distributed data set, find the value of the standard deviation if the following information is given. a. The mean is 226.2. x = 230. z = 0.2. Standard deviation
*April 1, 2014 by Sarah Nichols*

**Statistics**

he life expectancy of a lung cancer patient treated with a new drug is normally distributed with a mean of 4 years and a standard deviation of 10 months
*September 30, 2012 by Ty*

**statistics**

Section 5.3: Normal Distributions: Finding Values Answer the questions about the specified normal distribution. Q1: The lifetime of ZZZ batteries are normally distributed with a mean of 265 hours and a standard deviation ó of 10 hours. Find the number of hours that represent ...
*March 28, 2010 by looking for someone to varify my work please*

**statistics**

. For patients with a certain disease the amount of certain protein in the blood is normally distributed with a mean of 130 and a standard deviation of 5. For patients without the disease the amount of that protein is normally distributed with a mean of 150 and a standard ...
*October 29, 2014 by Anonymous*

**statistics**

For patients with a certain disease the amount of certain protein in the blood is normally distributed with a mean of 130 and a standard deviation of 5. For patients without the disease the amount of that protein is normally distributed with a mean of 150 and a standard ...
*October 30, 2014 by Anonymous*

**statistics**

Can you please tell me how to solve for the following? Pedro took an exam in a class in which the mean was 64 with a standard deviation of 6. If his z score was +3, what was his exam score? A students commute to school is normally distributed with a mean of 31 min and a ...
*July 28, 2013 by Sandra*

**Analytical Skills**

If your score on a statistics exam was 76 and the professor gave you the distribution for the exam score for your class, you could find your percentile to understand where you stand in comparison to your fellow students. Assume that the distribution for exam scores is normally...
*October 6, 2011 by Jojo*

**Statistics**

find the 90% confidence interval for the variance and standard deviation of the ages of seniors at Oak Park College if a sample of 24 students has a standard deviation of 2.3 years. Assume the variable is normally distributed. Can someone explain the steps to solve this? ...
*October 26, 2010 by Diandra*

**Statistics**

Given that x is a normally distributed random variable with a mean of 28 and a standard deviation of 7, find the following probability: P(x<28) I understand that the means is 28 and the standard deviation is 7. However what I don't understand is how to get the value of x. ...
*October 9, 2012 by Anonymous*

**Math**

This is my sample: 29,083 ; 25,314, 31,920 ; 30,750 ; 32,302 I need to find the mean and standard deviation of this sample?! How can i assure the life spans are normally distributed?
*May 6, 2015 by Aqueen*

**college**

Assume that the life expectancy of U.S. males is normally distributed with a mean of 80 years and a standard deviation of 4 years. What is the probability that a randomly selected male will live more than 85 years?
*April 29, 2010 by Brittney*

**Statistics**

An electrical firm which manufactures a certain type of bulb wants to estimate its mean life. Assuming that the life of the light bulb is normally distributed and that the standard deviation is known to be 40 hours, how many bulbs should be tested so that we can be 90 percent ...
*November 16, 2012 by Blerp*

**Statistics**

Mileage tests were conducted on a randomly selected sample of 100 newly developed automobile tires. The results showed that the average tread life was 52,515 miles with a standard deviation of 3,550 miles. What is the best estimate of the average tread life in miles for the ...
*April 20, 2014 by Ray*

**math**

The life span of a DVD player produced by one major company is known to be normally distributed with a mean of 6.2 years. If 4.01% of these DVD players have a life span of more than 8 years, what is the standard deviation of the DVD player’s life span?
*April 15, 2015 by ananya*

**Algebra **

Mr. Smith has 100 students in his Algebra classes. The grades of a quiz are normally distributed with a mean of 70 and a standard deviation of 4. Sally claims that 75 students scored between 66 and 74 on this quiz. Given that this is normally distributed, is Sally correct?
*March 2, 2015 by Help is needed *

**Statistics**

Are these statements true or false? 1. The sample mean, the sample proportion and the sample standard deviation are all unbiased estimators of the corresponding population parameters. 2. If the population is normally distributed with known variance then the sample mean may not...
*November 5, 2010 by help*

**statistic**

Two samples each of size 25 are taken from independent populations assumed to be normally distributed with equal variances. The first sample has a mean of 35.5 and standard deviation of 3.0 while the second sample has a mean of 33.0 and standard deviation of 4.0. The pooled (i...
*March 17, 2015 by joanne*

**algebra**

Mr. Smith has 100 students in his Algebra classes. The grades of a quiz are normally distributed with a mean of 70 and a standard deviation of 4. Sally claims that 75 students scored between 66 and 74 on this quiz. Given that this is normally distributed, is Sally correct? ...
*March 1, 2015 by dumb boy*

**algebra**

Mr. Smith has 100 students in his Algebra classes. The grades of a quiz are normally distributed with a mean of 70 and a standard deviation of 4. Sally claims that 75 students scored between 66 and 74 on this quiz. Given that this is normally distributed, is Sally correct? ...
*March 1, 2015 by please help me*

**Math**

Random variables X and Y are both normally distributed with mean 100 and standard deviation 4. It is known that random variable X+Y is also a normal distribution. a. What is the mean of X+Y? b. What is the standard deviation of X+Y? I see that the mean is 200 but I don't know ...
*November 15, 2011 by Rob*

**math**

Mr. Smith has 100 students in his Algebra classes. The grades of a quiz are normally distributed with a mean of 70 and a standard deviation of 4. Sally claims that 75 students scored between 66 and 74 on this quiz. Given that this is normally distributed, is Sally correct? ...
*March 1, 2015 by Kid with help fast*

**Statisitcs**

The mean height of fully grown birch trees are 18 feet with a standard deviation of 1.2 feet, normally distributed. Random samples of size 9 are drawn from this population and the mean of each sample is determined. Find that mean and the standard error of the mean, and the ...
*November 14, 2012 by D*

**MATH; STANDARD DEVIATION**

suppose that prices of a certain model of new homes are normally distributed with a mean of $150,000 use 68-95-99.7 rule to find the percentage of buyers who paid: between $150,000 and $152,000 if the standard deviation is $1200
*April 29, 2015 by CHIN*

**statistics**

Assume that a population is normally distributed with a mean of 100 and a standard deviation of 15.
*September 26, 2011 by michelle*

**stats**

Opisthotrochopodus n sp. is a polychaete worm that inhabits deep sea hydrothermal vents along the Mid-Atlantic Ridge. According to an article by Van Dover et al. in Marine Ecology Progress Series (1999, vol 181 pp 201-214), the lengths of female polychaete worms are normally ...
*March 14, 2013 by Anonymous*

**adult education**

The lifetimes of lightbulbs of a particular type are normally distributed with a mean of 290 hours and a standard deviation of 6 hours. What percentage of the bulbs have lifetimes that lie within 1 standard deviation to either side of the mean?
*May 23, 2009 by sally*

**Word Problem**

A math teacher gives two different tests to measure students' aptitude for math. Scores on the first test are normally distributed with a mean of 25 and a standard deviation of 4.6. Scores on the second test are normally distributed with a mean of 68 and a standard deviation ...
*March 7, 2010 by Lyndse*

**Statistics**

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

**math**

A medical researcher believes that the standard deviation of the temperatures of newborn infants is greater than 0.6 degrees. A sample of 15 infants was found to have a standard deviation of 0.8 degrees. At the 0.10 level of significance, does the evidence support the ...
*October 5, 2014 by Ina*

**statistics**

Assuming that the data are normally distributed with a mean of 45 and a standard deviation of 3.25, what is the z-score for a value of 40?
*October 20, 2011 by Dean*

**statistics**

The life span of the battery pack is known to be Normally distributed with a mean of 250 hours and a standard deviation of 20 hours. How to find the percentage of the battery packs lasting more than 250 hrs.
*May 6, 2012 by noe*

**Finite Math**

If the life in years, of a television set is normally distributed with a mean of 46 years and a standard deviation of 4 years, what should be the guarantee period if the company wants less than 3% of the television sets to fail while under warranty?
*February 13, 2010 by Maria*

**statistics**

Use the Standard Normal Distribution table to find the indicated area under the standard normal curve. Q1: Between z = 0 and z = 2.24 A1: 0 = 0.5000 2.24 = 0.9875 0.9875 – 0.5000 = 0.4875 Q2:To the left of z = 1.09 A2: 0.8621 Q3: Between z = -1.15 and z = -0.56 A3: -1.15 = 0....
*March 27, 2010 by looking for someone to varify my work please*

**Statistics**

A random variable X is normally distributed with ì = 60. Convert the value of X to a z-score, if the standard deviation is as given. X = 60; ó = 7 A) 7 B) 1 C) 60/70 D) 0
*March 2, 2011 by Megan*

**Statistics**

A random variable X is normally distributed with ì = 60. Convert the value of X to a z-score, if the standard deviation is as given. X = 60; ó = 7 A) 7 B) 1 C) 60/70 D) 0
*March 2, 2011 by Megan*

**Statistics**

X is normally distributed with a mean of 250 and a standard deviation of 40. What value of X does only the top 15% exceed?
*September 16, 2011 by Joi*

**statistics**

Suppose that is normally distributed with mean 90 and standard deviation 12. What value of does only the top 20% exceed?
*September 19, 2011 by sarah *

**statistics**

Assuming that the data are normally distributed with a mean of 45 and a standard deviation of 3.25, what is the z-score for a value of 40? (Points : 6) 1.54 2.38 -1.36 -1.54
*October 19, 2011 by Anonymous*

**ivy tech**

Assuming that the data are normally distributed with a mean of 45 and a standard deviation of 3.25, what is the z-score for a value of 40?
*August 30, 2012 by ann*

**stats**

if x is a normally distributed random variable with amean of 8.00 if the proability for x is less than 9.54 is 0.67, then find the standard deviation of x
*October 21, 2012 by tamara*

**statistics**

Given a normally distributed population of values with a mean of 76 and a standard deviation of 10 what is the probability that a value is 71 and 82
*September 9, 2014 by bono*

**stats**

The life of tires manufactured by Omega Tires Inc is believed to be normally distributed with a mean of 110,000 km and a standard deviation of 5,000 km. A random sample of 200 tires is tested . What is the problability of the mean life of this sample being between 109,000 and ...
*October 9, 2012 by Carlos*

**statistics**

It is well known that the heights of individual American men are normally distributed with mean 70 inches and standard deviation 2.8 inches. The Central Limit Theorem states that if n men are randomly chosen, then their average height will also be normally distributed with ...
*February 13, 2011 by LISA*

**stat**

for randomly selected adults, IQ scores are normally distributed with a standard deviation of 15. the scores of 14 randomly selected college students are listed below. use a 0.10 significance level to test the claim that the standard deviation of IQ scores of college students ...
*May 14, 2012 by carl*

**statistics**

The lifetimes of light bulbs of a particular type are normally distributed with a mean of 370 hours and a standard deviation of 5 hours. What percentage of bulbs has lifetimes that lie within 1 standard deviation of the mean on either side?
*January 12, 2015 by Michael*

**stats**

Assume that aset of test scores is normally distributed with a mean of 100 and a standard deviation of 20 use the 68-95-99?
*July 4, 2010 by Anonymous*

**statistics**

the random variable x is normally distributed with a mean of 75 and a standard deviation of 15.0. For this distribution, what is the twenty-third percentile?
*August 20, 2010 by marie*

**statistics**

Scores on an english test are normally distributed with a mean of 33.6 and a standard deviation of 8.3. Find the 41st percentile?
*November 1, 2010 by English Test Scores*

**Math**

Random variable X is normally distributed with mean 10 and standard deviation 2. Compute the following probabilities. a. Pr(X<10) b. Pr(X<11.04) I don't know where to start.
*November 10, 2011 by Sally*

**MATH**

At one college, GPA’s are normally distributed with a mean of 2.9 and a standard deviation of 0.6. Find the 70th percentile.
*August 7, 2014 by KDIZZLE*

**Statistics**

At one college, GPA’s are normally distributed with a mean of 2.9 and a standard deviation of 0.6. Find the 70th percentile.
*December 2, 2014 by justice*

**statistics**

The most common intelligence quotient (IQ) scale is normally distributed with mean 100 and standard deviation 15. What score would put a child 3 standard deviations above the mean
*September 3, 2012 by Gee*

**statistics**

The most common intelligence quotient (IQ) scale is normally distributed with mean 100 and standard deviation 15. What score would put a child 3 standard deviations above the mean
*September 3, 2012 by Gee*

**statistics**

IQ scores distribution of IQ scores is not normally distributed standard with a mean of 100 and a standard deviation of 15, which is represented by a bell-shaped graphical. What is the area under the curve? What is the median? What is the mode?
*April 25, 2015 by norma*

**statistics**

IQ scores distribution of IQ scores is normally distributed standard with a mean of 100 and a standard deviation of 15, which is represented by a bell-shaped graphical. What is the area under the curve? What is the median? What is the mode?
*April 25, 2015 by norma*

**STATISTICS**

IQ scores distribution of IQ scores is normally distributed standard with a mean of 100 and a standard deviation of 15, which is represented by a bell-shaped graphical. What is the area under the curve? What is the median? What is the mode?
*April 25, 2015 by norma*

**college math**

Math homework please help!! 2. Suppose that people’s weights are normally distributed, with mean 175 pounds and a standard deviation of 6 pounds. Round to the nearest hundredth of a percent a. What percent of the population would weigh between 165 and 170 pounds? b. What ...
*November 5, 2013 by lynda*

**statistics**

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

**Stats**

Suppose the time it takes for a purchasing agent to complete an online ordering process is normally distributed with a mean of 8 minutes and a standard deviation of 2 minutes. Suppose a random sample of 25 ordering processes is selected. The standard deviation of the sampling ...
*November 13, 2011 by Jerry*

**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**

IQ scores are normally distributed with a mean of 105 and a standard deviation of 18. Assume that many samples of size n are taken form a large population of people and the mean IQ score is computed for each sample. If the sample size is n=64, find the mean and standard ...
*September 13, 2012 by kimberly*

**statistics**

if the mean of a normally distributed set of data is 100 and the standard deviation is 10, a z score of 2 corresponds to raw value of?
*November 2, 2010 by g*

**statistics**

A population is normally distributed with a man of 100 and a standard deviation of 15. is it unusual for themean of a sample of 3 to be 115 or more? Why or why not?
*January 30, 2012 by Donna*

**statistics**

Scores on an English test are Normally distributed with a mean of 78% and a standard deviation of 4.5%. Find the Value of the first quartile.
*December 3, 2012 by ray*

**statistics**

skating speeds are normally distributed with a mean of 60 and a standard deviation of 10. Determine the speed that separates the top 6% from the rest.
*November 13, 2013 by peter*

**statistics**

the dean of admissions in a large university has determined that the scores of the freshman class in a mathematics test are normally distributed with a mean of 86 and a standard deviation of 11. A sample of 50 students is selected at random from the entire freshman class. ...
*March 26, 2012 by Pat*

**statistics**

Cholesterol levels of adult males are approximately normally distributed with a mean of mg/dL and a listed standard deviation of . Some researchers claim that the standard deviation of cholesterol levels of adult males is less than . Suppose that we want to carry out a ...
*February 27, 2010 by anaya*

**statistics**

An investment broker reports that the yearly returns on common stocks are approximately normally distributed with a mean return of 12.4 percent and a standard deviation of 20.6 percent. On the other hand, the firm reports that the yearly returns on tax-free municipal bonds are...
*February 19, 2012 by Anonymous*

**math**

kris scored 630 points on a particular section of a CPA exam for which the score were normally distributed with a mean of 600 points and a standard deviation of 75 points. At a differenttime, kerry scored 540 points on the same section, for which scores were normally ...
*April 12, 2011 by kaleb*

**math**

kris scored 630 points on a particular section of a CPA exam for which the score were normally distributed with a mean of 600 points and a standard deviation of 75 points. At a differenttime, kerry scored 540 points on the same section, for which scores were normally ...
*April 13, 2011 by shirley*

**finite math**

kris scored 630 points on a particular section of a CPA exam for which the score were normally distributed with a mean of 600 points and a standard deviation of 75 points. At a differenttime, kerry scored 540 points on the same section, for which scores were normally ...
*April 14, 2011 by margie*

**algebra 2**

The time it takes for climbers to reach the highest point of a mountain is normally distributed with a standard deviation of 0.75 hours. If a sample of 35 people is drawn randomly from the population, what would be the standard error of the mean of the sample?
*May 21, 2014 by bc*

**sample size/ standard deviations**

How do we compute sample size fluctuations? Suppose we have a population of 16000 and a sample size of 30, and the number of samples 1000, what will be the impact on population mean and standard deviation when the population is normally distributed? When the population is ...
*December 1, 2011 by ut*

**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.
*April 29, 2012 by Kim*

**statistics**

Let x be a continuous random variable that is normally distributed with a mean of 65 and a standard deviation of 15. Find the probability that x assumes a value less than 44.
*April 18, 2011 by Katie*

**statistics**

Let x be a continuous random variable that is normally distributed with a mean of 65 and a standard deviation of 15. Find the probability that x assumes a value less than 45.
*April 18, 2011 by Katie*

**statistics**

In a population of normally distributed aptitude scores of 1000 academy students with mean 70 and Standard deviation 10, how many score above 95?
*May 10, 2011 by Lisa*

**statistics**

Let x be a continuous random variable that is normally distributed with a mean of 65 and a standard deviation of 15. Find the probability that x assumes a value less than 44.
*October 31, 2012 by Anonymous*

**math**

on a mathematics test in high school, scores are normally distributed with a mean of 77 and a standard deviation of 16.8. A students is randomly selected.
*February 1, 2014 by Anonymous*

**Stats**

4) The amount of Jen’s monthly phone bill is normally distributed with a mean of $50 and a standard deviation of $10. Find the 25th percentile.
*July 18, 2015 by Anonymous*

**Elementary statistics **

Scores on an English test are normally distributed with a mean of 78% and a standard deviation of 4.5%. Find the value of the first quartile.
*July 20, 2015 by Lizzy*

**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
*March 28, 2010 by yolanda*

**statistics**

Suppose scores on the mathematics section of the SAT follow a normal distribution with mean 540 and standard deviation 120. ACT math scores are normally distributed with a mean of 18 and a standard deviation of 8. What score on the ACT is equivalent to a score of 750 on the SAT
*September 15, 2013 by Anonymous*

**math**

Instant dinner comes in packages with weights that are normally distributed, with a standard deviation of 0.3 oz. If 2.3% of the dinners weigh more than 13.5 oz, what is the mean weight?
*November 15, 2008 by missy*

**statistics**

The mean (μ) of the scale is 98 and the standard deviation (σ) is 13. Assuming that the scores are normally distributed, what is the PROBABILITY that a score falls below 88?
*February 28, 2012 by Anonymous*

**Math**

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.
*May 21, 2013 by Denise*

**statistics**

A psychologist studied self esteem scores and found the sample data set to be normally distributed with a mean of 50 and a standard deviation of 5?
*January 25, 2014 by Stephanie*

**algebra2**

Scores on a test are normally distributed with a mean of 75 and a standard deviation of 8. Estimate the probability that a randomly selected student scored between 71 and 75.
*August 4, 2014 by clara*

**ashworth college**

The amount of Jen’s monthly phone bill is normally distributed with a mean of $50 and a standard deviation of $10. Find the 25th percentile
*December 2, 2014 by justice*

**statistics**

The mean (μ) of the scale is 83 and the standard deviation (σ) is 10. Assuming that the scores are normally distributed, what is the PROBABILITY that a score falls below 72?
*March 12, 2015 by chris*

**statistics**

The actual weights of bag of pet food are normally distributed.The mean of the weights is 50.0 lb,with a standard deviation of 0.2 lb. C)In a group of 50 bags,how many would yu expect to be within 1.5 standard deviations of the mean?
*June 4, 2012 by Anonymous*

**statistik**

can you show me the calculation ;) The life expectancy of computer terminals is normally distributed with a mean of 4 years and standard deviation for 10 months. a. What is the probability that a randomly selected terminal will last more than 5 years? b. What percentage of ...
*December 2, 2012 by mira*