Thursday

September 29, 2016
Number of results: 9,754

**quanitative methods**

The time required to complete a project is known to be normally distributed with a mean of 44 weeks and a standard deviation of 8 weeks. (a) What is the probability that the project is finished in 40 weeks or fewer?

*February 5, 2014 by Anonymous*

**statistics**

If 1,000 students take a test that has a mean of 40 minutes, a standard deviation of 8 minutes, and is normally distributed, how many would you expect would finish in between 24 and 48 minutes?

*August 6, 2014 by pablo*

**Math**

Suppose you have a mean standardized score of 1500 points with a standard deviation of 150 points. This data is normally distributed. What is the z-score of 1600 points? 0.75 0.5 0.67 0.32

*May 31, 2015 by Destiny*

**statistics**

at a bank, account balances are nomrally distribued with a mean of $637.52 and standard deviation of $623.16. What is the probability that a simple randon same of 400 accounts has mean that exceeds $1650.00? show me steps and calculations i urgently need help

*January 23, 2008 by son*

**statistics**

Please let me know if I solved this right The lifetime of television produced by the Hishobi Company are normally distributed with a mean of 75 months and a standard deviation of 8 months. If the manufacturer wants to have to replace only 1% of its televisions, what should its...

*February 11, 2011 by Holly*

**statistics**

1. The average number of articles produced by two machines per day is 200 and 250 with standard deviation 20 and 25 respectively on the basis of records of 25 days production. Can you regard both the machines equally efficient at 1% level of significance?

*March 5, 2012 by lokesh*

**statistics**

A balloon mannufacturer kows that historically her company has produced 614 balloons per day (standard deviation =36) she has changed the process and wants to know wheathert he new process is increased the number of ballons made. the sample mean is 620. 0.5, n=16

*March 5, 2013 by kim*

**statistics**

The serum cholesterol levels for men in in one age group are normally distributed with mean of 178.1 and standard deviation of 40.8. All units are in mg/100ml. Find two levels that cut off the top 10% and the bottom 10 % from the distribution of x.

*October 30, 2013 by Amy*

**statistics**

Assume that thermometer readings are normally distributed with a mean of 0.0 and a standard deviation of 1,00. the thermometer is randomly selected and tested. For the case below, draw a sketch , and find the probability of the reading The given values in Celsius degrees) ...

*November 22, 2013 by judy*

**Basic Statistics**

A researcher is interested in estimating the average salary of police officers in a large city. She wants to be 95% confident that her estimate is correct. If the standard deviation is $1050,how large a sample is needed to get the desired information and to be accurate within...

*October 15, 2014 by John*

**state **

A machine put the juice in the bottle with normal distribution with mean is equal to 50 cl, with the standard deviation 5 cl. Test was done to see if the claim is right. A sample of 100 bottles were tested. They got the average content of 48.9 cl. At ∝ =0.05, can the ...

*December 11, 2015 by iram*

**Algebra**

I do not understand this homework at all. Any help or elaboration would be greatly appreciated. Thanks. 100 juniors at Southwest High took the SAT test. The scores were distributed normally with a mean of 22 and a standard deviation of 3. Label the mean and three standard ...

*April 12, 2016 by Kesha*

**maths**

The data in table below gives marks for an exam of a particular tutors students in 2005 and 2006. Year students marks on the exam 2005 75 86 91 65 83 75 88 90 66 99 2006 60 78 75 98 79 90 80 88 81 90 from the following choose two options which are true about the table above. a...

*May 19, 2007 by angel*

**Algebra 2**

Suppose you did a survey of male shoes size and the mean of that survey was size 10 with a standard deviation of 1.5. What is the z-score of a size of 7.5?

*June 7, 2011 by Adam*

**Math**

Suppose you did a survey of male shoes size and the mean of that survey was size 10 with a standard deviation of 1.5. What is the z-score of a size of 7.5?

*June 7, 2011 by Wyeth*

**Stats**

A Math test has a mean of 51 and standard deviation of 5.0. Find the corresponding z scores for: I. a test score of 64 II. a test score of 47

*October 15, 2011 by Jennifer*

**probability**

normally distributed with a mean of 40 minutes and a standard deviation of 5 minutes. What is the probability that it will take more than 40 minutes? Answer

*January 24, 2012 by Dillon*

**Help please! Math **

A car is designed to last an average of 12 years with a standard deviation of 0.8 years. What is the probability that a car will last less than 10 years?

*January 12, 2014 by Katalina*

**Statistics**

A criminologist is studying school violence, she selects a random sample of 25 adolescents aged 12 to 15 from a local middle school and asks the following,"How many times within the past school year have you been physically assaulted at school? She calculated the following ...

*February 27, 2015 by Elena *

**Stats**

The average price for new mobile homes is known to be distributed with a standard deviation of 350. if a random rample of 49 homes resulted in a sample mean of 38500, obtain a 90% confidence interval on the population mean.

*March 24, 2009 by Sally*

**bus. stats**

Given that math SAT scores are normally distributed (follow the empirical rule) m=500 Standard deviation=100 what is the math SAT score for someone who is in the 80th percentile of his or her class.

*March 3, 2010 by mike*

**bus. stats**

Given that math SAT scores are normally distributed (follow the empirical rule) m=500 Standard deviation=100 what is the math SAT score for someone who is in the 80th percentile of his or her class.

*March 3, 2010 by mike*

**business research **

The standard deviation of the sample is 0.4. Over the last 10 years, the average GPA has been 3.0. Is the GPA of this years students significantly different from the long-run average? At what alpha level would it be significant

*March 8, 2010 by joi*

**Statistics**

19. George got 70% on an economics exam where the mean was 55% and the variance was 9. If a professor wishes to change the distribution of marks so that they have a mean of 70% and a standard deviation of 5, what will Georges new mark be? a) 95% b) 85% c) 90% d) Over 100% The...

*October 23, 2010 by Rhea *

**Quantitative methods**

the mean and standard deviation of the grades of 500 students who took an maths exam were 69 and 7 respectively. if the grades have a bell shaped distribution, how many of these students received a grade of more than 83 marks?

*April 7, 2011 by lisa*

**Quantitative methods**

the mean and standard deviation of the grades of 500 students who took an maths exam were 69 and 7 respectively. if the grades have a bell shaped distribution, how many of these students received a grade of more than 83 marks?

*April 7, 2011 by lisa*

**mathematical modeling**

Use the 68-95-99.7 rule to solve: The amount of Jen's monthly phone bill is normally distributed with a mean of $48 and a standard deviation of $6. Fill in the blanks. 95% of her phone bills are between $_____ and $_____.

*March 27, 2012 by Jeremiah*

**economics**

the average tax charge is $95. Assuming a normal distribution as a standard deviation of $10, use the approximate areas beneath the normal curve to answer what proportion of tax prep fees were exactly $100?

*December 15, 2012 by Anonymous*

**statistics**

Your samle is normally distributed with a mean age of 57. The standard deviation iin this sample is 5 years.The 2000 census shows your sample is older than a randomly selected national sample. The median agein your sample is?

*June 3, 2013 by statistics*

**Math IV**

what is the margin of error for a simple random sample of 900 people with a standard deviation of 13.5 at 95% level of confidence How do you write this question in the right formula, please? I believe I can calculate the problem, I don't know how to write it. 900 2.5 and 1.96

*August 20, 2014 by Darryl*

**Statistics**

Below are the numbers of games played in the World Series from 1903 to 2012. Find the mean, variance and standard deviation. Games played Probability 4 0.186 5 0.231 6 0.203 7 0.341 8 0.039

*February 20, 2015 by E.man*

**MATH**

A food snack manufacturer samples 15 bags of pretzels off the assembly line and weighed their contents.If the sample mean is 10.0 and the sample standard deviation is 0.15, find the 95% confidence interval of the true mean.

*April 16, 2015 by GRACE*

**math**

Adult IQ scores are normally distributed with mean 100 and standard deviation 15. Find the IQ score that separates the adults with the highest 3% of IQ scores from the rest of the adults. Round your answer to the nearest whole number.

*March 31, 2016 by anon*

**stats**

Using the following data set a. Calculate the mean, mode, median, standard deviation, minimum, maximum and range b. Draw the histogram of the data set. Use 100 as bin width

*April 16, 2016 by ABDULA YUSUF*

**stats**

Using the following data set a. Calculate the mean, mode, median, standard deviation, minimum, maximum and range. b. Draw the histogram of the data set. Use 100 as bin width.

*April 17, 2016 by Anonymous*

**Statistics **

Suppose a fair coin is tossed five times and let x be the number that turned up in those five times. **the mean and the standard deviation are respectively... a.) 0.5, 0.5 b.) 2.5, 0.5 c.) 2.5, 2.24 d.) 2.5, 1.12 **find P(x≥1) a.) 0.5 b.) 1.0 c.) 0.03 d.) 0.97 * i just ...

*May 30, 2016 by Caitlyn *

**Statistics **

From a sample with n equals=24, the mean number of televisions per household is 3 with a standard deviation of 1 television. Using Chebychev's Theorem, determine at least how many of the households have between 1 and 5 televisions.

*September 18, 2016 by Addison*

**math**

2 51 45 58 41 44 37 38 40 44 45 40 59 45 44 34 44 43 48 32 38 1.Determine the mean of the data 2.Determine the standard deviation of the data

*May 19, 2013 by jacob*

**ap statistics**

What is the mean of the sample means? What is the standard deviation of the sample means?

*April 24, 2014 by emma*

**ap statistics**

What is the mean of the sample means? What is the standard deviation of the sample means?

*April 25, 2014 by emma*

**Algebra**

The mean is 18.1 the data set for 13 is -1.7 What is the standard deviation for this data set.

*July 27, 2015 by Malu*

**statistics**

The daily sales of a retail store are normally distributed with a standard deviation of $500. If the probability that sales will be less than $10,000 in any one day is 40%, what are the mean daily sales?

*April 23, 2013 by Anonymous*

**Statistics **

The daily sales of a retail store are normally distributed with a standard deviation of $500. If the probability that sales will be less than $10,000 in any one day is 40%, what are the mean daily sales?

*April 22, 2015 by Anonymous*

**Statistics**

ATM transaction times are normally distributed with a mean of 150 seconds and a standard deviation of 45 seconds. What is the probability a person takes less than 60 seconds to complete their transaction?

*February 19, 2016 by Anonymous*

**stat**

The ministry of transport and communication is responsible for the enforcement of airline safety regulations and has become concerned about an apparent increase in accidents and near mishaps involving commercial aircraft. One area of concern is overloading due to passenger ...

*August 23, 2014 by LwEeNdO *

**Statistics**

It is known that the amount of time needed to change the oil in a car is normally distributed with a standard deviation of 5 minutes. A random sample of 100 oil changes yielded a sample mean of 22 minutes. Compute the 99% confidence interval estimate of the mean of the ...

*February 26, 2007 by Jason L*

**math**

The diameter of an electric cable is normally distributed, with a mean of 0.8 inch and a standard deviation of 0.01 inch. What is the probability that the diameter will exceed 0.83 inch? (Give the answer to four decimal places.)

*August 30, 2011 by Anonymous*

**Math**

The diameter of an electric cable is normally distributed, with a mean of 0.8 inch and a standard deviation of 0.01 inch. What is the probability that the diameter will exceed 0.83 inch? (Give the answer to four decimal places.)

*August 24, 2011 by Lee Ann*

**math**

The diameter of an electric cable is normally distributed, with a mean of 0.8 inch and a standard deviation of 0.01 inch. What is the probability that the diameter will exceed 0.82 inch? (Give the answer to four decimal places.)

*August 24, 2011 by apryl*

**alegbra**

The diameter of an electric cable is normally distributed, with a mean of 0.8 inch and a standard deviation of 0.01 inch. What is the probability that the diameter will exceed 0.82 inch? (Give the answer to four decimal places.)

*August 27, 2011 by apryl*

**people**

Suppose that people's heights (in centimeters) are normally distributed, with a mean of 165 and a standard deviation of 6. We find the heights of 80 people. (a) How many would you expect to be between 159 and 171 cm tall?

*December 11, 2011 by Anonymous*

**statistics**

the life of electric bulbs has a normal distribution with a mean of 35 months and a standard deviation of 4 months. What should the warranty period be if the company that manufactures these bulbs does not want to replace more than 2% of the bulbs?

*December 19, 2011 by HELPME*

**algebra**

The diameter of an electric cable is normally distributed, with a mean of 0.8 inch and a standard deviation of 0.01 inch. What is the probability that the diameter will exceed 0.81 inch? (Give the answer to four decimal places.)

*February 28, 2012 by Anonymous*

**stats**

a sample of 16 atm transactions shows a mean transaction time of 67 seconds with a standard deviation of 12 seconds. State the hypotheses to test whether the mean transactiontime exceeds 60 seconds

*February 29, 2012 by Anonymous*

**math**

The diameter of an electric cable is normally distributed, with a mean of 0.8 inch and a standard deviation of 0.01 inch. What is the probability that the diameter will exceed 0.81 inch? (Give the answer to four decimal places.)

*June 9, 2012 by Anonymous*

**staticstics**

The average length of an adult blue whate is 30 meters with a standard deviation of 5.7 meters. If a sample of 31 whales is taken, what is the probability that their average lenght differs from the mean by more than 2.0 meters

*October 17, 2012 by melinda*

**staticstics**

The average length of an adult blue whate is 30 meters with a standard deviation of 5.7 meters. If a sample of 31 whales is taken, what is the probability that their average lenght differs from the mean by more than 2.0 meters

*October 17, 2012 by melinda*

**statistics**

All deal with a random variable X that follows a normal probability distribution with mean equal to 37 and a standard deviation of 5. Compute P(X < 39) Compute P(X < 29 or X > 41) Compute P(X > 30) Find the 42nd percentile for this distribution.

*April 25, 2013 by luke*

**statistics**

All deal with a random variable X that follows a normal probability distribution with mean equal to 37 and a standard deviation of 5. Compute P(X < 39) Compute P(X < 29 or X > 41) Compute P(X > 30) Find the 42nd percentile for this distribution.

*April 25, 2013 by luke*

**statistics**

if a toaster ovens hav an average life expectancy of 9.5 years with a standard deviation of 4.75 years. what is the probability that a toaster oven will last twenty years or will fail in one year or less?

*September 21, 2013 by efe*

**Statistics**

Suppose that the average weight of students in a statistics class is 75.5 kilograms with a standard deviation of 10.3 kilograms. A. 45% of the student weights are above ____ kilograms? Z=.3264=x-75.5/10.3 Now what? I am lost! Please help me! Thanks!

*February 10, 2014 by Anonymous*

**Statistics**

Suppose that the average weight of students in a statistics class is 75.5 kilograms with a standard deviation of 10.3 kilograms. A. 45% of the student weights are above ____ kilograms? Z=.3264=x-75.5/10.3 Now what? I am lost! Please help me! Thanks!

*February 10, 2014 by Anonymous*

**statics**

Walleye is a common game fish. Adult walleye have a length with a mean of 44 cm and a standard deviation of 4 cm and the distribution of lengths is approximately Normal. What fraction of walleye are longer than 52 cm in length?

*June 22, 2015 by angel*

**statistics**

Given a sample size of 36, with sample mean 400 and sample standard deviation 85, we perform the following hypothesis test, at the 95% level of confidence: Ho: = 450, Ha: 450. What is the question and what is the answer?

*December 8, 2015 by Anonymous*

**Math**

The diameters of bolts produced by a certain machine are normally distributed with a mean of 0.25 inches and a standard deviation of 0.01 inches. What percentage of bolts will have a diameter greater than 0.24 inches? A. 79.13% B. 82.46% C. 84.13% D. 84.46% answer:C

*May 4, 2016 by angela*

**Biostatics**

Walleye is a common game fish. Adult walleye have a length with a mean of 48 cm and a standard deviation of 3 cm and the distribution of lengths is approximately Normal. What fraction of walleye are shorter than 45 cm in length?

*June 8, 2016 by Lisa*

**statistics**

You are designing a study to determine whether music has an effect on learning. Previous research indicates that the standard deviation to learn a task is 3.4 minutes. How many subjects would you need to ensure with 90% confidence that the estimate is within 1 minute of the ...

*April 29, 2012 by tammy*

**FINANCIAL ACCOUNTING**

A portfolio manager is managing a $10 million portfolio. Currently the portfolio is invested in the following manner: Investment Dollar Amount Invested Beta Electric Utility $2 million 0.6 Cable Company $3 million 0.8 Real Estate Development $3 million 1.2 International ...

*November 15, 2012 by Yinka*

**Statistics**

Suppose the mean height of a population is 65 inches with a standard deviation of 1.5 inches. What is the z value for a height (x) of 67 inches?

*May 4, 2011 by Erik *

**math**

Suppose the mean height of a population is 65 inches with a standard deviation of 1.5 inches. What is the z value for a height (x) of 67 inches?

*October 25, 2011 by Daniela*

**statistics**

Suppose the mean height of a population is 65 inches with a standard deviation of 1.5 inches. What is the z value for a height (x) of 67 inches?

*May 15, 2012 by Anonymous*

**statistics**

Suppose the mean height of a population is 65 inches with a standard deviation of 1.5 inches. What is the z value for a height (x) of 67 inches?

*August 18, 2012 by deja*

**Statistics**

Suppose the mean height of a population is 65 inches with a standard deviation of 1.5 inches. What is the z value for a height (x) of 67 inches?

*November 1, 2012 by jassi*

**Statistics**

For Mathguru_ from statistic question on Tuesday April 10, 2007 follow up question- what if I wasn't given the standard deviation either- how would I solve this problem Other tutors can help, but without the previous information, it is impossible to help you. Please repost ...

*April 11, 2007 by Angel*

**Math**

The Lifetimes of a certain brand of photographic light are normally distributed with the mean of 210 h and a standard deviation of 50 h. What percent of lights will need to be replaced within 233 h? Out of 2000 lights, how many will have a lifetime between 200 h and 400 h?

*June 9, 2011 by Jerry*

**statistics**

A researcher is interested in estimating the noise levels in decibels at area urban hospitals. She wants to be 95% confident that her estimate is correct. If the standard deviation is 4.02, how large a sample is needed to get the desired information to be accurate within 0.58 ...

*September 2, 2011 by Laynette*

**Statistics**

An automatic machine in a manufacturing process is operating properly if the lengths of an important subcomponent are independently and normally distributed with a mean of 120 cm and a standard deviation of 4.7 cm. Find the probability that if 3 are randomly selected, all 3 ...

*September 21, 2011 by Meghan*

**statistics**

Let's pretend the Work variable is normally distributed, with a mean/median/mode value of 22 and a standard deviation of 17. Based on these numbers, we can say that approximately 50 percent of SOC 390 students work more than ____ hours per week

*November 4, 2011 by Sarah*

**statistics**

LSAT test scores are normally distributed with a mean of 510 and a standard deviation of 110. Find the probability that a randomly chosen test-taker will score between 300 and 580. (Round your answer to four decimal places.)

*November 21, 2012 by Anonymous*

**statistics**

LSAT test scores are normally distributed with a mean of 490 and a standard deviation of 110. Find the probability that a randomly chosen test-taker will score between 320 and 600. (Round your answer to four decimal places.)

*April 16, 2013 by jack*

**statistics**

In a test of the effectiveness of garlic for lowering cholesterol, 44 subjects were treated with garic in a processed tablet form. Cholesorol levels were measured before and after the treament. the changes in their levels of LDL cholestorol (in mg/dL have a mean of 3.5 and a ...

*March 1, 2015 by slomomo*

**Math**

The percent of fat calories that a person in America consumes each day is normally distributed with a mean of about 36 and a standard deviation of about 10. Suppose that 16 individuals are randomly chosen. Is it appropriate to use the normal approximation for the sampling ...

*November 20, 2015 by Brandy*

**Statistics**

The lifetime of a 2-volt non-rechargeable battery in contant use has a normal distribution with a mean of 516 hours and a standard deviation of 20 hours. Ninety percent of all batteries have a lifetime less than ?

*September 2, 2009 by Karen*

**Statistics**

The lifetime of a 2-volt non-rechargeable battery in contant use has a normal distribution with a mean of 516 hours and a standard deviation of 20 hours. Ninety percent of all batteries have a lifetime less than ?

*September 2, 2009 by Karen*

**statistics**

Assume that the mean hourly cost to operate a commercial airplane follows the normal distribution with a mean of $2,225 per hour and a standard deviation of $220. What is the operating cost for the lowest 5 percent of the airplanes?

*November 21, 2010 by Barbara*

**Math - Data Management**

I'm kinda stuck on my math homework, does anyone know how to do it? The results of a blood test at a medical lab are normally distributed with a mean of 60 and a standard deviation of 15. How low must a score be to lie in the lowest 5% of the results?

*June 9, 2011 by Andy*

**statistics**

the average starting salary is Rs 15000per month with a standard deviation of Rs.1000 assuming normal distribution,what is the probability that starting salary will be more than Rs.17000, out of 200 degree holders how many will getRs.14000?

*August 7, 2011 by Anonymous*

**Statistics**

Commuters were asked how many times a week they stop for coffee on their way to work. A survey found a mean of 3 times a week with a standard deviation of 0.55. Find the probability that the sum of 121 values is less than 350.

*December 3, 2012 by Alley*

**statistics**

A food snack manu. samples 15 bags of pretzels off the assembly line and weighed their contents. If the sample mean is 10.0 and the sample standard deviation is .15, find the 95% confidence interval estimate for the true mean.

*January 3, 2013 by Kelly*

**Analytical Chemistry **

The question: The pH of a solution is defined as pH = -log[H3O+]. If the pH of a solution is 3.72(+/- 0.03), what is the [H3O+] and its absolute standard deviation? Answer: How would I carry this out? I know to find the hydronium concentration wouldn't i just take e^3.72? How ...

*January 28, 2013 by James*

**Statistics for Development**

one hundred students seat for a mathematics examination.the scores from this examination are normaly distributed with a population mean of 65% and a standard deviation of (a=10).what is the probability that students score;(i)less than 75% (ii)at least85% (iii)between 60% and 75%

*April 16, 2013 by Benson*

**statistics**

The lifetime of a 2-volt non-rechargeable battery in constant use has a normal distribution with a mean of 516 hours and a standard deviation of 20 hours. Ninety percent of all batteries have a lifetime less than

*May 31, 2013 by Anonymous*

**math 115**

Let x be a continuous random variable that follows a normal distribution with a mean of 200 and a standard deviation 25. Find the value of x so that the area under the normal curve between and x is approximately 0.4798 and the value of x is greater than .

*November 19, 2013 by louise*

**Statistics**

Hello, my problem is I have a random sample of only 15 sales average is $115 with a known population standard deviation of $25.00. Obtain a 92% confidence interval and explain what your answer means. I am not sure what to do because the sample size is only 15. Thanks for your ...

*November 29, 2013 by kim*

**statistics**

The true highway mileage, Y, of a specific brand of hybrid vehicle has a normal distribution with a mean of 42 and a standard deviation of 1.5. Find the probability that a randomly selected hybrid vehicle gets more than 38 miles to the gallon.

*June 17, 2014 by lisa*

**stats**

Commuters were asked how many times a week they stop for coffee on their way to work. A survey found a mean of 3 times a week with a standard deviation of 0.55. Find the probability that the sum of 100 values is more than 290.

*July 10, 2014 by brewster*

**math**

Commuters were asked how many times a week they stop for coffee on their way to work. A survey found a mean of 3 times a week with a standard deviation of 0.55. Find the probability that the sum of 100 values is more than 290.

*July 12, 2014 by brewser*

**Stat**

Thirty randomly selected students took the calculus final. If the sample mean was 89 and the standard deviation was 6.2, construct a 99% confidence interval of the mean score of all students. Assume that the population has a normal distribution

*October 1, 2014 by Anonymous*

**Statistics**

Assume that the mean hourly cost to operate a commercial airplane follows the normal distribution with a mean of $2,325 per hour and a standard deviation of $240. What is the operating cost for the lowest 5 percent of the airplanes?

*October 9, 2014 by Dany*

**7th grade math standard form scientific notation**

In standard form: 5. 3.2 x 10^3 7. 4.1 x 10^8 9. Write the average weight of a blue whale, 2.6 x 10^5, in standard form. 15. 2.5 x 10^-3 17. 1.05 x 10^-2 19. Write the size of a grain of very fine sand, about 9.35 x 10^-3 cm, in standard form. Can somebody help? I have been ...

*September 28, 2012 by Delilah*