Monday

July 28, 2014

July 28, 2014

Number of results: 7,857

**Hypothesis testing**

5 Part Question: 6 timed runs were made along route A with an average of 95 minutes and a standard deviation of 10.5 minutes. Route B had 8 test runs with an average of 93 minutes and a standard deviation of 5.2 minutes. Determine if there sufficient evidence that route B is ...
*April 2, 2010 by Moe*

**Prob ans stat**

Let x be a random variable that represents the length of time it takes a student to complete a take-home exam in Dr. Larson's psychology class. After interviewing many students, it was found that x has an approximately normal distribution with mean of 5.2 hours and standard ...
*July 29, 2011 by Hannah*

**math**

The lengths of what are considered "1 inch bolts are found to be normally distrubted with a mean of 1.001 inches and a standard deviation of 0.002 inches. If a bolt measures more than 2 standard deviations away from the mean, it is rejected for not meeting factory tolerances. ...
*April 12, 2011 by david*

**maths**

Please help with this question.The mean weight of the contents of samples of 30 bags of sugar has standard error 0.008kg.The mean is 1.0042kg.Standard deviation is 0.042kg Choose the option that is closest to the probability, to three decimal places, that the mean weight of ...
*June 5, 2011 by Rebecca*

**statistics/ please help ASAP**

a set of data is normally distributed with a mean of 500 and a standard deviation of 100. a) what would the standard score fora score of 700 be? b) what % of scores is between 500 and 700? c) what would the percentile rank for a score of 700 *please show and answer all ...
*October 28, 2010 by vedry frustrated please help and show work*

**Pre-calculus**

A set of data is normally distributed with a mean of 500 and a standard deviation of 40. What percent of the data is between 460 and 540? Answer: 68.3%
*October 8, 2008 by Lucy*

**stats**

How large a sample should be taken if the population mean is to be estimated with 99% confidence to within $72? The population has a standard deviation of $800 Please Help, im stuck
*November 17, 2008 by ks*

**Math**

If each score in a set of test scores is divided by 10, describe the effect of the division on the mean, median, mode, range, and standard deviation of the set.
*January 9, 2010 by Anna*

**Math & Data Management**

The height of baby tree are normally distributed with a mean of 31.5 cm and a standard deviation of 10 cm. What is the height above which 85% of the seedlings have grown?
*June 15, 2010 by Madmazel*

**Statistics**

IQ test scores are normally distributed with a mean of 97 and a standard deviation of 11.An individual's IQ score is found to be 123.Find the z-score corresponding to this value
*November 2, 2010 by Rachel*

**statistics**

Assuming the resting heart rates for a sample of individuals are normal distibuted with a mean of 70 and a standard deviation of 15. Waht percentage of rates less than 70
*November 12, 2010 by Darlene Watson*

**Statistics**

The weights of adult males are normally distributed with a mean of 172 lb and a standard deviation of 29 lb Q.Find the weight that divides the upper 2% of weights from the lower 98%
*March 10, 2011 by Nathan*

**Statistics**

Use the Empirical Rule to find what two values 95% of the data will fall between for a data set with a mean of 294 and standard deviation of 13.
*May 16, 2011 by Denise*

**statistics**

A 95% confidence interval for a population mean was reported to be 23,100 to 24,900. If the sample standard deviation is 5,808.26, what sample size was used in this study?
*June 5, 2011 by Anige*

**Help plz!! Math....**

Start with x = 100 and add four x values to make a sample of five data such that the standard deviation of these data equals 0
*October 12, 2011 by Jen*

**Stats**

Given the following frequency distribution, find the mean, variance, and standard deviation. Please show all of your work. Errors Frequency 51-53 9 54-56 19 57-59 16 60-62 24 63-65 25
*October 13, 2011 by Jennifer*

**Statistics**

a machine fills containers with a standard deviation of filling weights of 1.5. calculate the mean weight if only 4 % of the containers hold less than 19 ounces
*November 16, 2011 by Jerry*

**statisticas**

A 82% confidence interval for a sampling distribution with a mean of 100, a sample standard deviation of 24 and a sample size of 36 will be based on a á= ______ and a corresponding Zá of ____
*January 28, 2012 by Jason*

**Statistics**

A 82% confidence interval for a sampling distribution with a mean of 100, a sample standard deviation of 24 and a sample size of 36 will be based on a á= ______ and a corresponding Zá of ___
*March 5, 2012 by Jeff*

**Statistics**

A 82% confidence interval for a sampling distribution with a mean of 100, a sample standard deviation of 24 and a sample size of 36 will be based on a á= ______ and a corresponding Zá of ___
*March 5, 2012 by Jeff*

**statistics**

At the end of the festival the organizers estimated that a family of participants spent an average of $90.00 with a standard deviation of $15.00. What’s the probability that the mean amount spent will be NO more than $75?
*March 21, 2012 by Diane*

**Statics**

Given the following frequency distribution, find the mean, variance, and standard deviation. Please show all of your work. Class Frequency 61-63 19 64-66 17 67-69 5 70-72 10 73-75 12
*June 21, 2012 by kesha*

**Math**

Consider the following test scores obtained by a class. Test score 90 80 70 60 50 Frequency 1 4 11 6 2 Find the standard deviation (rounded to the nearest hundredth).
*December 4, 2012 by Debin*

**Statistics**

The amount of rainfall in January in a certain city is normally distributed with a mean of 4.2 inches and a standard deviation of 0.5 inches. Find the value of the quartile Q1
*April 21, 2013 by Sennie *

**statistics**

12 squirrels were found to have an average weight of 10.5 ounces with a sample standard deviation is 0.25. Find the 95% confidence interval of the true mean weight
*May 8, 2013 by Anonymous*

**help**

Assume that the salaries of elementary school teachers in the U.S. are normally distributed with a mean of $37,000 and standard deviation of $3500. The cutoff salary for teachers in the bottom 12% is
*October 13, 2013 by Anonymous*

**Statistics**

A population has a standard deviation of 15.2. How large a sample must be drawn so that a 95% confidence interval for the population mean will have a margin error equal to 3.5?
*March 26, 2014 by Nicole*

**Statistics**

A study found that 8-to 12-year olds spend an average of $18.50 per trip to mall. If a sample of 49 children was used, find the 99% confidence inteval of the mean. Assume the standard deviation is $1.50.
*November 20, 2008 by Anonymous*

**MAth**

Scores of an IQ test have a bell shaped distribution with a mean of 100 and a standard deviation of 19. Use the empirical rule to determine the following. a.) What % of people has an IQ score between 81 and 119?
*July 17, 2012 by quita*

**statistics**

Working on "Inferences from Dependent Samples" trying to find the standard deviation of the difference data. Differences: 24, 53, 100, 40, -10,71,77,70, 39, 50 n=10 d=51.4 sd=??? (Answer suppose to be 30.8336 but not coming close to this number at all)
*November 30, 2012 by HELP*

**MATH**

Working on "Inferences from Dependent Samples" trying to find the standard deviation of the difference data. Differences: 24, 53, 100, 40, -10,71,77,70, 39, 50 n=10 d=51.4 sd=??? (Answer suppose to be 30.8336 but not coming close to this number at all)
*November 30, 2012 by Inferences from Dependent Samples*

**statistics**

Shoppers were asked how much money they were going to spend today in the mall. The mean dollars was $250 with a standard deviation of $15. In a group of 64 people, what is the probability that they spent less than $240?
*December 3, 2012 by Alley*

**Statistics**

Assume that adults have IQ scores that are normally distributed with a mean of 100 and a standard deviation of 15. Find the IQ score separating the top 37% from the others. Answer in one decimal place.
*March 28, 2014 by Tracy*

**Math**

The average hourly wage of employees of a certain company is $14.58. Assume the variable is normally distributed. If the standard deviation is $3.99, find the probability that a randomly selected employee earns less than $9.79.
*July 12, 2014 by Shelagh*

**Math**

The average hourly wage of employees of a certain company is $14.24. Assume the variable is normally distributed. If the standard deviation is $3.27, find the probability that a randomly selected employee earns more than $18.98.
*July 12, 2014 by Shelagh*

**math**

You manage inventory for your company and use a continuous review inventory system to control reordering items for stock. Your company is open for business 310 days per year. One of your most important items experiences demand of 24 units per day, normally distributed with a ...
*July 17, 2012 by Candace*

**Math Quantitive Reasoning**

The amount of Jen's monthly phone bill is normally distributed with a mean of $50 and a standard deviation of $12. What percentage of her phone bills are between $14 and $86?
*December 2, 2007 by Lindsey*

**Statistics**

Some IQ scores are standardized with a mean of 100 and a standard deviation of 16. Using the 68-95-99.7 Rule, Determine: In what interval you would expect the middle 95% of the IQ scores to be found.
*February 25, 2008 by Math help*

**statistics**

When you add the values 3, 5, 8,12, and 20 and then divide by the number of values, the result is 9.6. Which term best describes this value: average, mean, median, mode, or standard deviation?
*April 19, 2010 by Anonymous*

**trig**

the scores on a 100 pt test are normally distributed with a mean of 80 and a standard deviation of 6. a student's score places him between the 69th and 70th percentile. what is his score?
*June 10, 2010 by cliff*

**statistics**

Let’s assume you have taken 100 samples of size 36 each from a normally distributed population. Calculate the standard deviation of the sample means if the population’s variance is 25.
*June 13, 2010 by Anonymous*

**statistics**

When you add the values 3, 5, 8, 12, and 20 and then divide by the number of values, the result is 9.6. Which term best describes this value: average, mean, median, mode, or standard deviation?
*June 29, 2010 by Anonymous*

**staticis**

3. When you add the values 3, 5, 8, 12, and 20 and then divide by the number of values, the result is 9.6. Which term best describes this value: average, mean, median, mode, or standard deviation
*September 7, 2010 by Norma*

**Statisitcs**

Scores on the verbal section of the SAT have a mean of 500 and a standard deviation of 100. If someone scored at the 90th percentile, what is their SAT score?
*October 31, 2010 by Johnny*

**statistics**

the j.o supplies company buys calculators from a supplier. The probability of a defective calculator is 10%. If 100 calculators are selected at random, what is the standard deviation of the number of defectives.
*December 10, 2010 by Anonymous*

**statistics**

Scores on the ACT test are normally distributed with a mean of 21.1 and a standard deviation of 4.8. If one ACT score is randomly selected, find the probability that it is greater than 20.
*December 14, 2010 by Abby*

**math**

The University Entrance scores are normally distributed with a mean of 250 and a standard deviation of 30. What is the probability that a randomly selected student scored lower than 250?
*May 25, 2011 by Probability*

**Statistics**

A distribution of 800 test scores in a biology course was approximately normally distributed with a mean of 35 and a standard deviation of 6. Calculate the proportion of scores falling between 20 and 40
*June 18, 2011 by Fred*

**statistics**

The weights of certain machine components are normally distributed with a mean of 9.75g and a standard deviation of 0.08g. Find the weights that separate the top 5% and the bottom 5%.
*June 22, 2011 by Jessica*

**Elementray Statistics**

Assume that a population is normally distributed with a mean of 100 and a standard deviation of 20. Would a sample mean of 115 or more be considered unusual? Why or why not?
*August 3, 2011 by Alice*

**algebra**

In a set of 400 values, the mean is 121 and the standard deviation is 14. Estimate how many values fall in between each interval. a) 107 - 135 = b) 93 - 149 = c) 79 - 163 =
*September 23, 2011 by twan*

**Stats.....plz help me.....**

Given the following frequency distribution, find the mean, variance, and standard deviation. Please show all of your work. Errors Frequency 51-53 9 54-56 19 57-59 16 60-62 24 63-65 25
*October 14, 2011 by Jennifer*

**statistics**

a test has a mean score 73 with standard deviation of 12.students with scores greater than 85 recieve an A. What is the percent of the students would we expect to get an A? assume the normal distribution
*November 28, 2011 by Kathleen*

**Probability and statistics**

2. The standard deviation of the number of tosses required to get a 1 when a balanced dice is tossed repeatedly is equal to Choose one answer: a. √6 b. √30 c. 6 d. 30
*March 2, 2012 by Arun*

**statistics**

If the grades on a police entrance exam are normally distributed with a mean of 100 and a standard deviation of 15, what percentage of students received grades of less than 115?
*April 1, 2012 by Laura*

**algebra**

In a set of 400 values, the mean is 121 and the standard deviation is 14. Estimate how many values fall in between each interval a) 107 - 135 b)93 - 149 c) 79 - 163
*June 2, 2012 by arron*

**statistics**

1- The ages of a population of 300 is normally distributed, with a mean of 45 and a standard deviation of 4. If you randomly selected a member of the population, what is the probablity that his or her age would be greater than 49?
*June 11, 2012 by Gloria*

**math**

The ages of a population of 300 is normally distributed, with a mean of 45 and a standard deviation of 4. If you randomly selected a member of the population, what is the probablity that his or her age would be greater than 49?
*June 11, 2012 by Gloria*

**statistics**

mean cholesterol is 175mg/dl..standard deviation =20mg/dl assume approx normal distribution ..is varied. what percentage has a cholesterol level above 155mg/dl?
*July 7, 2012 by michelle*

**Math**

Dorian's score of 558 on the writing portion of the 2009 SAT exam placed him in the 72nd percentile. If the mean on this exam was 493, what was the standard deviation?
*November 13, 2012 by Angie*

**STATISTICS**

ASSUME THE THE MEAN WEIGHT OF CHILDREN AGES 7 IS 50 POUNDS AND A STANDARD DEVIATION OF 10. wHAT IS THE PROBABLITY THAT A RANDOM SELECTED 7 YEAR OLD WILL HAVE A WEIGHT THAT IS LESS THAT 65
*February 11, 2013 by SONIA GOVAN*

**stats**

Thirty random students took the final. If the sample mean was 86 and the standard deviation was 9.2 construct a 99 percent confidence interval for the mean score of all
*April 15, 2013 by t*

**statistics**

When you add the values 3, 5, 8, 12, and 20 and then divide by the number of values, the result is 9.6. Which term best describes this value: average, mean, median, mode, or standard deviation?
*April 22, 2013 by Anonymous*

**math**

Assume you do not know the population standard deviation. describe how you form a 90% confidence interval to estimate the population mean age for students at Westwood College Online.
*May 1, 2013 by ruby*

**math**

Some books give the following rule of thumb for finding the standard deviation of a normally distributed variable: s= range/6. Explain why this rule works.
*May 3, 2013 by Moyer*

**math**

In a set of 400 values, the mean is 121 and the standard deviation is 14. Estimate how many values fall in between each interval? a) 107 - 135 b)93 - 149 c) 79 - 163
*May 6, 2013 by takierr*

**statistics**

the mean of sat scores of a specific month is1000 with a standard deviation of 100. find the 90 percentiles . assume that the sat score is normal distributed
*June 18, 2013 by Alex*

**Math**

Assume that the mean salary for a profession is $35,104 with a standard deviation of $3200. What percent of the profession earns less than $38,700? I dont understand how to do this. Please help!!
*November 7, 2013 by Kim*

**statistics**

If a data set has a mean of 10.0 seconds and a standard deviation of 2.0 seconds, what is the Z score corresponding to the time of 4.0 seconds?
*August 14, 2010 by Desiree *

**statistics**

if a data se has a mean of 10.0 seconds & a standard deviation of 2.0 seconds, what is the z score corresponding to the time of 4.0 seconds?
*February 18, 2011 by thelma*

**statistics**

if a sample of a distribution of sample size 26 has a range of 56, then what would be an estimate of the sample standard deviation
*February 14, 2013 by karen*

**statistics**

What percentages of students studied 30 hours or less? These hours ranged between 10-50 hours with a mean of 35 and a standard deviation of 5.
*October 14, 2010 by kim*

**statistics**

What percentages of students studied 30 hours or less? These hours ranged between 10-50 hours with a mean of 35 and a standard deviation of 5.
*October 14, 2010 by kim*

**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
*April 29, 2012 by julie*

**Statistics**

Assume x is normally distributed with mean µ= 15 and standard deviation α= 3-. Use the approximate areas beneath the normal curve, as discussed in this section, to answer the following questions. Find P (X ≥15)- A) 0.50 B) 0.16 C) 0.34 D) 0.84
*February 22, 2009 by Stuart*

**statistics**

use the given information to find the minimum sample size required to estimate an unknown population mean. Margin of error/; $137, confidence level:99%, standard deviation = $535
*July 24, 2011 by susan*

**Statistics**

The heights in inches of 14 randomly selected adult males in LA are listed as: 71, 67, 70, 59, 71, 68, 67, 71, 80, 68, 74, 69, 72, 68 Display the data in a stem and leaf plot. find the mean, median, mode, range, variance, and standard deviation.
*September 18, 2011 by Lisa *

**statistics**

The scores on an economics examination are normally distributed with a mean of 66 and a standard deviation of 14. If the instructor wishes to assign a grade of A to the top 10% of the class, what is the lowest score a student may have and still obtain an A?
*November 6, 2011 by Anonymous*

**statistics**

Scores on a certain nationwide college entrance examination follow a normal distribution with a mean of 400 and a standard deviation of 100. Find the probability that a student will score over 500.
*December 18, 2011 by Kelly*

**statistics**

Q) 75% of the population in Guinea, Africa is infected with malaria. Suppose a physician sees 6 patients in a given hour. Assuming these conditions are met, find the mean and standard deviation of the distribution. Help please!
*August 9, 2012 by nick*

**statistics**

a population has mean 15 and standard deviation 5. if 68% of the values in the population are between 10 and 20, the population cannot be normal
*July 11, 2011 by nikki*

**statistics**

what is the proportion of people who drink more than 20 gallons of cofffee per year if the mean is 24.2 gallons and the standard deviation is 8.1 gallons
*April 6, 2012 by Anonymous*

**check math problem**

(c) The number of cars found to have unsafe tires among the 379 cars stopped at a roadblock for inspection (assume that 15% of all cars have one or more unsafe tires). (i) Find the mean. (Give your answer correct to one decimal place.) 56.85. (ii) Find the standard deviation...
*June 7, 2013 by tommy512*

**math**

A researcher predicts that listening to music while solving math problems will make a particular brain area more active. To test this, a research participant has her brain scanned while listening to music and solving math problems, and the brain area of interest has a ...
*August 15, 2011 by Donna*

**statistics**

Calculate SS, variance, and standard deviation for the following sample of n=9 scores:2,0,0,0,0,2,0,2,0.(Note: The computational formula for SS works best with these scores.) I keep getting the wrong numbers. Thank You.
*January 29, 2008 by Tracy*

**statistics**

The Intelligence Quotient (IQ) test scores are normally distributed with a mean of 100 and a standard deviation of 15. What is the probability that a person would score 130 or more on the test?
*December 8, 2008 by Robby*

**stats**

The incomes of trainees at a local mill are normally distributed with a mean of $1100 and a standard deviation $150. What percentage of trainees earn less than $900 a month?
*July 20, 2010 by J.T.*

**statistics**

the amount of time spent in North American adults watching television per day is normal distributed with a mean of 6 hours and a standard deviation of 1.5 hours
*September 6, 2010 by Marcus *

**Statistics**

Which of the following is true about Standard Deviation? a. It is the maximum value minus the minimum value b. It a range of values c. It the average d. It a measure of spread e. It measures location
*September 15, 2010 by Beata Chmielewska*

**statistics**

Consider a normal distribution with mean 30 and standard deviation 6. What is the probability a value selected at random from this distribution is greater than 30? (Round your answer to two decimal places.)
*October 22, 2010 by Anonymous*

**MATH**

THE MEAN PRICE OF DIGITAL CAMERAS AT AN ELECTRONIS STOR IS $224, WITH A STANDARD DEVIATION OF $8. RANDOM SAMPLES OF SIZE 36 ARE DRAWN FROM THIS POPULATION AND THE MEAN OF EACH SAMPLE IS DETERMINED.
*November 4, 2010 by caintgetrite*

**statistics**

Suppose we have a set of body temperature with a mean of 97.6 degrees and a standard deviation of 0.3 degrees. between what two values should 99% of all temperatures lie?
*November 25, 2010 by Debora*

**statistics**

For a chapter on the Central Limit Theorem; I have a Uniform Distribution problem were a & b are not given. Only the average, standard deviation, and sample size are given. How do you find a & b?
*May 15, 2011 by Anonymous*

**statistics**

Assume that a set of test scores is normally distributed with a mean of 80 and a standard deviation of 25. Use the 68-95-99.7 rule to find the following quantities. The percentage of scores less than 80 is?
*May 24, 2011 by nicole*

**Statistics Math Help**

A distribution of 800 test scores in a biology course was approximately normally distributed with a mean of 35 and a standard deviation of 6. Calculate the proportion of scores falling between 20 and 40
*June 18, 2011 by Fred*

**business statistics**

A 82% confidence interval for a sampling distribution with a mean of 100, a sample standard deviation of 24 and a sample size of 36 will be based on a á= ______ and a corresponding Zá of ____ .18 and .47 .18 and .915. .09 and .23 .09 and 1.34
*July 11, 2011 by CS*

**statistics**

For a hypothetical normal distribution of test scores, approximately 95% fall between 38 and 62, 2.5% are below 38, and 2.5% are above 62. Given this information, (a) the mode=_____ and (b) the standard deviation=_____.
*October 26, 2011 by Scott F*

**Statistics**

The grades for Economics students at a large university are found to be normally distributed with a mean of 76 and a standard deviation of 4. What proportion of the students are expected to have a grade between 84 and 88?
*November 24, 2011 by Brea*

**statistics**

The time required to travel downtown at am on Monday morning is known to be normally distrubted with a mean of 40 minutes and a standard deviation of 5 minute what is the probability that it will take less than 40 minutes?
*January 19, 2012 by john kollie*

**statistics**

Suppose a college's SAT scores are normally distributed with mean 1000 and standard deviation 1 for students above 1200. What percentage of students is eligible for scholarships
*September 19, 2012 by iroc*

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