Tuesday

October 21, 2014

October 21, 2014

Number of results: 37,686

**statistics**

2. The director of admissions at a large university advises students that the cost of textbooks will average more than $300 for a typical semester. A random sample of 80 students enrolled in the university shows a sample mean cost of $315.40 and a sample standard deviation of...
*August 22, 2010 by Elizabeth*

**Chemistry**

A 23.596 g sample of aqueous waste leaving a fertilizer manufacturer contains ammonia. The sample is diluted with 79.504 g of water. A 13.803 g aliquot of this solution is then titrated with 0.1098 M HCl. It required 29.02 ml of the HCl solution to reac the methyl red endpoint...
*November 14, 2011 by Mike*

**chemistry**

A 23.596 g sample of aqueous waste leaving a fertilizer manufacturer contains ammonia. The sample is diluted with 79.504 g of water. A 13.803 g aliquot of this solution is then titrated with 0.1098 M HCl. It required 29.02 ml of the HCl solution to reac the methyl red endpoint...
*November 14, 2011 by Mike*

**Basic Statistics **

A population of 200 voters contains 52 Republicans, 128 Democrats, and 20 independents and members of other parties. A simple random sample of 20 voters will be drawn from this population. The expected number of Republicans in the sample is ______ ? The standard error of the ...
*July 25, 2011 by mike*

**chemistry**

A sample of an ideal gas at 1.00 atm and a volume of 1.61 L was placed in a weighted balloon and dropped into the ocean. As the sample descended, the water pressure compressed the balloon and reduced its volume. When the pressure had increased to 45.0 atm, what was the volume ...
*April 6, 2012 by catey*

**chemistry**

A 4.691 g sample of MgCl2 is dissolved in enough water to give 750. mL of solution. What is the magnesium ion concentration in this solution?
*October 4, 2010 by nalleli*

**Chemistry**

A 4.379 g sample of MgCl2 is dissolved in enough water to give 750.0 mL of solution. What is the chloride ion concentration in this solution?
*April 14, 2014 by Chris*

**AP chemistry**

A 28 g sample of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 19.5 g. What was the mass of iron in the sample of ore? Answer in units of g.
*August 3, 2010 by Tasha*

**Chemisrty **

A 38 g sample of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 11.1 g. What was the mass of iron in the sample of ore? Answer in units of g
*August 31, 2011 by Stoichiometry*

**chemistry**

A 12.8 g sample of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 21.3 g. What was the mass of iron in the sample of ore? Answer in units of g
*September 2, 2012 by Emily*

**AP Chemistry**

A 7.6 g sample of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 12.9 g. What was the mass of iron in the sample of ore? Answer in units of g
*September 3, 2012 by Rafael*

**AP Chemistry**

A 12 g sample of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 27.6 g. What was the mass of iron in the sample of ore? Answer in units of g
*August 29, 2013 by Gabriella*

**AP Chemistry**

A 37.5 g sample of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 17.8 g. What was the mass of iron in the sample of ore? Answer in units of g
*September 2, 2013 by Anonymous*

**chemistry**

Upon decomposition, one sample of magnesium fluoride produced 1.65kg of magnesium and 2.58kg of fluorine. A second sample produce 1.38kg of magnesium. How much fluorine (in grams) did the second sample produce?
*September 3, 2013 by tatianna*

**Chemistry**

Upon decomposition, one sample of magnesium fluoride produced 1.65kg of magnesium and 2.58kg of fluorine. A second sample produced 1.38kg of magnesium. How much fluorine (in grams) did the second sample produce?
*September 7, 2013 by Anonymous*

**Chemistry**

Upon decomposition, one sample of magnesium fluoride produced 1.65kg of magnesium and 2.58kg of fluorine. A second sample produced 1.38kg of magnesium. How much fluorine (in grams) did the second sample produce?
*September 7, 2013 by Anonymous*

**statistics**

A random sample of 10 observations has been drawn from a normal population, and the sample variance is found to be s² = 19.5. Determine the 98% confidence interval for ó².
*August 12, 2009 by Laura*

**statistics**

A random sample of n= 12 is drawn from a population that is normally distributed, and the sample variance is s©÷ = 19.3. Use ¥á = 0.025 in testing ¥Ç₀ : ¥ò©÷ ¡Â 9.4 versus ¥Ç©û : ¥ò©÷ > 9.4
*August 12, 2009 by Yadira M*

**Chemistry**

The titration of a sample of a weak acid with an equivalent weight of 108 grams requires 38.2 mL of 0.100 M NaOH. What is the sample mass in mg?
*November 30, 2009 by Telly*

**Chemistry**

10% of a sample reacts in 25 s. If the reaction follows first order kinetics, how long would it take for half the sample to react?
*May 3, 2010 by mandy*

**Statistics**

An urn contains 8 chips, numbered 1 through 8. A sample of 3 is drawn without replacement. What is the probability that the largest chip in the sample is a 5?
*June 24, 2011 by Nicholas*

**statistics**

A sample mean with a z-score value between -1.00 and +1.00 would be considered a fairly typical representative sample. True or False
*October 30, 2011 by Betty*

**chemistry**

An analytical chemist determines that an unknown sample contains 0.3452 mol of LiCl. How many atoms of chlorine does this sample contain?
*December 1, 2011 by jack*

**math**

can someone please explain to me what happens to the mean and standard deviation of the distribution of sample means as the size of the sample decreases?
*February 11, 2013 by kacie*

**Chem**

A 4.96L sample of chlorine gas is contained in a poison control vessel at STP. Calculate the number of grams in this sample
*September 29, 2013 by Joe*

**Chemistry**

AgNO3 + NaCl → AgCl + NaNO3 . How many grams of NaCl would be required to react with 446 mL of 0.211 M AgNO3 solution? Answer in units of grams
*February 21, 2014 by Zoey*

**chmeistry**

50 ml of 0.1 M NaCl is mixed with 50 ml of 0.2 M AgNO3 predict whethera ppt of AgCl is formed or not
*April 10, 2010 by Anonymous*

**MATH!**

The mass of a radioactive substance follows an exponential decay model, with a decay rate of 5% per day. A sample of this radioactive substance was taken six days ago. If the sample has a mass of 3 kg today, find the initial mass of the sample. Round your answer to two decimal...
*March 15, 2012 by Kim*

**Chemistry **

Ascorbic acid (vitamin C) is a diprotic acid having the formula H2C6H6O6. A sample of a vitamin supplement was analyzed by titrating a 0.3252 g sample dissolved in water with 0.0284 M NaOH. A volume of 13.27 mL of the base was required to completely neutralize the ascorbic ...
*February 25, 2014 by Anonymous*

**Chemistry**

Ascorbic acid (vitamin C) is a diprotic acid having the formula H2C6H6O6. A sample of a vitamin supplement was analyzed by titrating a 0.3252 g sample dissolved in water with 0.0284 M NaOH. A volume of 13.27 mL of the base was required to completely neutralize the ascorbic ...
*February 25, 2014 by PM*

**statistics**

My mean is 175.5 My standard deviation is=90.57 Sample=25 Formula to be used: P(X>190)=P((X-mean)/s sqrt of my sample is = 5 (Which is the square root of 25.)(190-175.5) / 90.57/5) 14.5/18.114 calculator says 0.8004858120790548746825659710721 I check the z-table ...
*May 27, 2013 by Ann*

**Chemistry**

Why is a blank solution used in absorption spectroscopy? I know it is to nullify the reflection, refraction, and diffraction that occurs, but if the blank solution was a dilute solution rather deionized water, how would the concentration of Cr(VI)in a sample be affected?
*February 25, 2014 by Sandy*

**statistics **

in the spring of 2001, a university had 40,000 registered students. to estimate the percentage of all students expecting to graduate in 4 years, a simple random sample of 225 students was drawn, 144 of the sample planned to graduate in 4 years. (a) were the draws made with or ...
*May 8, 2014 by anonymous*

**Chemistry**

A sample of impure magnesium was analyzed by allowing it to react with excess HCl solution: Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g) After 1.27 g of the impure metal was treated with 0.100 L of 0.768 M HCl, 0.0125 mol HCl remained. Assuming the impurities do not react, what...
*September 22, 2013 by James*

**chemistry**

A 115 mL sample of a 10.0 M ethylene glycol (C2H6O2) solution is diluted to 1.30 L. What is the freezing point of the final solution? (Assume a density of 1.06 g/mL for the final solution.) What is the boiling point of the final solution? How would I go about setting this up? ...
*April 29, 2012 by Jen*

**Chemistry**

A sample of 0.30 moles of a metal M reacts completely with excess fluorine to form 18.69 grams of MF2. How many moles of F are in the sample of MF2 that forms? M + F2 ---> MF2 How many grams of M are in this sample of MF2 ?
*July 29, 2011 by Brooke*

**analytical chemistry**

Suppose a 4.272 g soil sample undergoes an extraction with 50 ml of extracting solvent to remove the lead. This 50 ml was then diluted to 250 ml and tested by atomic absorption technique. The concentration of lead in this diluted extract was found to be 35.7 ppm. What is the ...
*March 5, 2014 by Lori*

**Chemistry**

Upon decomposition, one sample of magnesium fluoride produced 1.65kg of magnesium and 2.58kg of fluorine. A second sample produced 1.50 kg of magnesium. How much fluorine (in grams) did the second sample produce?
*October 9, 2012 by Eliza*

**Analytical chemistry**

A 25.0-mL solution of 0.0660 M EDTA was added to a 33.0-mL sample containing an unknown concentration of V3 . All V3 present formed a complex, leaving excess EDTA in solution. This solution was back-titrated with a 0.0450 M Ga3 solution until all the EDTA reacted, requiring 13...
*April 4, 2013 by Ashley*

**Statistics**

In an essay of 250-500 words, thoroughly address the following items and respond to the related questions: 1.Define the term standard deviation. Why is it important to know the standard deviation for a given sample? What do researchers learn about a normal distribution from ...
*January 23, 2014 by Andrew*

**chemistry**

1. If a gaseous sample contains 73% N2 by volume, what is the solubility of N2 in water at 25°C and 1.0 atm (kH in H2O at 25°C = 7.0 10-4 mol/Latm)? 2. Calculate the vapor pressure of a solution of 0.60 mol of cholesterol in 4.5 mol of toluene at 32°C. Pure toluene has a vapor...
*January 31, 2011 by Ashley*

**chemistry**

Four solution are prepared and mixed together: Start with 100.0ml of 0.100M BaCl2. Add 50.0ml of 0.100M AgNO3. Add 50.0ml of 0.100M H2So4. Add 250.0ml of 0.100M NH4. Write an equation for any reaction that occurs after each step and calculate the concentration of Ba,CL,NO3,NH4...
*May 2, 2012 by Sean*

**college Geol 101**

Suppose you have a sample of clamshell at a Paleoindian site and you measure the 14C activity of a 100-gram sample of carbon as 320 disintegrations per minute (or 3.2 disintegrations per gram of carbon per minute). a.What was the activity (in disintegrations per minute) for ...
*October 20, 2010 by Jay*

**chemistry**

the pressure exerted on a 240.ml sample of hydrogen gas at constant temerature is increased from 0.428 to 0.724.What will the final volume of the sample be?
*October 20, 2010 by shubreet*

**statistics**

assuming a two tailed one sample test is being used,what ie the critical value for t given the following sample sizes. N=10 N=15 N=30
*April 24, 2011 by ryee*

**Math Stats**

A random sample of 30 plants has a sample standard deviation of 3.4 days for maturity. A 95% confidence interval for the population variance is __ to __days.
*March 28, 2012 by Apryl*

**Statistics**

A lottery uses 4 urns containing chips 0 to 9. One chip is selected at random from each urn. How many sample points are in the sample space?
*May 22, 2012 by Tammy*

**chemistry**

A sample of oxygen that occupies 1.00x10^6 mL at 575 mm Hg is subjected to a pressure of 1.36 atm. What will the final volume of the sample be if the temperature is held constant?
*February 27, 2013 by peyton*

**statistics**

True or False A sample mean with a z-score value between 1.00 and +1.00 would be considered a fairly typical, representative sample.
*January 3, 2014 by Lyndyc*

**statistics**

A lottery uses 4 urns containing chips 0 to 9. One chip is selected at random from each urn. How many sample points are in the sample space?
*January 18, 2014 by betty*

**Chemistry**

Suppose you are studying coordination compounds of Co(II) with the ligand pyridine (py, C5H5N, MW = 79.10). You isolate a crystalline compound and since the only available ions are chloride and nitrate, you hypothesize the empirical formula of the coordinaton compound must be ...
*April 20, 2007 by Ray*

**statistics**

a distribution of scores has 6, but the value of the mean is unknown, a researcher plans to select a sample from the population in order to learn more about the unknown mean, if the sample consist of n= 9 scores , how accurately should sample mean represent the population mean
*December 18, 2011 by herry*

**Statistics**

A sample of 12 measurements has a mean of 34 and a standard deviation of 4.5. Suppose that the sample is enlarged to 14 measurements, by including two additional measurements having a common value of 34 each. A. Find the mean of the sample of 14 measurements. Mean = B. Find ...
*April 29, 2010 by Jen*

**Chemistry**

It is possible, although less accurate, to do a standard addition with only one sample. An unknown Fe sample was analyzed by AAS and gave an absorbance reading of 0.160. To the same sample we added 1.5ppm Fe and the new absorbance reading was 0.205. Calculate the ppm of the ...
*March 5, 2012 by Mae*

**Chemistry**

It is possible, although less accurate, to do a standard addition with only one sample. An unknown Fe sample was analyzed by AAS and gave an absorbance reading of 0.160. To the same sample we added 1.5ppm Fe and the new absorbance reading was 0.205. Calculate the ppm of the ...
*March 5, 2012 by Ella*

**Math**

A 30% solution of fertilizer is to be mixed with a 60% solution of fertilizer in order to get 150 gallons of 50% solution. How many gallons of the 30% and the 60% solutions should be mixed. I really need help.
*February 1, 2011 by Candice Watt*

**science(chem)**

[b]1.[/b]Is TLC a qualitative or quantitative analysis? Is there any way that it can be both? Explain. ~I say it can be both since it can be used to go and determine what exactly is in a sample of mixed compounds which would be qualitative analysis. It can also be quantitative...
*October 13, 2007 by ~christina~*

**STAT**

Given a sample size of 18, with sample mean 660.3 and sample standard deviation 95.9, we are to perform the following hypothesis testing: Null Hypothesis H0 : µ = 700 Research Hypothesis H1 : µ ≠ 700 •What is the test statistics? •At a 0.05 significance level, what is ...
*October 12, 2013 by Jacky*

**STAT**

Given a sample size of 18, with sample mean 660.3 and sample standard deviation 95.9, we are to perform the following hypothesis testing: Null Hypothesis H0 : µ = 700 Research Hypothesis H1 : µ ≠ 700 •What is the test statistics? •At a 0.05 significance level, what is ...
*October 13, 2013 by Jacky*

**chemistry**

A 33.8 g sample of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 20.7 g. What was the mass of iron in the sample of ore?
*August 30, 2012 by Nick*

**Chemistry**

one sample of magnesium fluoride produced 1.65kg of magnesium and 2.58kg of fluorine. A second sample produced 1.31kg of magnesium. How much fluorine (in grams) did the second sample produce?
*September 26, 2013 by Jay*

**chemistry help!**

Potassium has an atomic mass of 39.10amu. a sample of potassium is made up of isotopes potassium-39 (mass=38.964) and potassium-41(mass =40.962 amu). What percentage of the potassium sample is potassium-39? what percent of the sample is potassium-41?
*October 20, 2011 by Skylar*

**business math**

Question: You receive the results of a paired-comparison preference these of four soft drinks from a sample of 200 persons. The results are as follows: Koak Zip Pabze Mr.Pep Koak ---- 50 115 35 Zip 150 --- 160 70 Pabze 85 40 --- 45 Mr.Pep 165 130 155 --- a). How does these ...
*December 1, 2007 by george*

**statistics**

. As a part of their customer-service program, United Airlines wanted to select 10 passengers from today's 9 A.M. Chicago-Tampa flight to be interviewed regarding airport facilities, service, and amenities in the waiting area. Each passenger was given a number on check in, ...
*November 14, 2011 by Latoya*

**Chemistry URGENT**

A student heated a hydrated salt sample with an initial mass of 4.8702 g, After the first heating, the mass had decreased to 3.0662 g (two part question) 1. if the sample was heated to constant weight after reheating, what is the minimum mass that the sample can have after the...
*April 26, 2014 by jazz*

**Statistics 2**

The body temperature of healthy human beings can be assumed to have a normal distribution with mean and standard deviation . Body temperature measurements taken from a sample of 130 healthy individuals shows the sample mean temperature to be 98.249O F and ...
*December 16, 2013 by Steven *

**t test **

how to know exact t value using sample standard deviation and sample mean and sample size i think df is sample size -1 . we usually use approx value but to use exact value how to use t score table. and how we conclude whether it is two tailed test or one tailed test . (i f the...
*July 18, 2010 by Anonymous*

**Chemistry**

Please let me know how I am doing with the following three chemistry questions. 1.A sample of a gas in thermometer has a volume of 135mL at 11 degree celcius.Indicat what temperature(in k and degree celcius)would correspond to the foll.volume: (a)volume:113mL temperature ?? ...
*November 23, 2010 by Cliff*

**Statistics**

A sample of purchases at the local convenience store has resulted in the following sample data, where x = the number of items purchased per customer and f = the number of customers. x 1 2 3 4 5 f 5 15 8 8 7 •What does the 15 stand for in the above table? •Find the midrange of ...
*October 17, 2011 by Jen*

**statistics t test **

how to know exact t value using sample standard deviation and sample mean and sample size i think df is sample size -1 . we usually use approx value but to use exact value how to use t score table. and how we conclude whether it is two tailed test or one tailed test . (i f the...
*July 18, 2010 by Anonymous*

**Chemistry**

What is the concentration of NO3- ions when equal volumes of 0.1M AgNO3 and 0.1M NaCl are mixed together?
*May 25, 2011 by Swathi*

**chemestiry**

Al2(SO4)3(aq) + BaCl2(aq) BaSO4(s) + AlCl3(aq) Consider the unbalanced equation above. A 0.680 g sample of impure Al2(SO4)3 reacts with excess BaCl2. If the sample produces 0.530 g of BaSO4, what is the mass percent of Al2(SO4)3 in the sample?
*March 20, 2013 by edi*

**chemestiry**

Al2(SO4)3(aq) + BaCl2(aq) BaSO4(s) + AlCl3(aq) Consider the unbalanced equation above. A 0.680 g sample of impure Al2(SO4)3 reacts with excess BaCl2. If the sample produces 0.530 g of BaSO4, what is the mass percent of Al2(SO4)3 in the sample?
*March 20, 2013 by edi*

**chemestiry**

Al2(SO4)3(aq) + BaCl2(aq) BaSO4(s) + AlCl3(aq) Consider the unbalanced equation above. A 0.680 g sample of impure Al2(SO4)3 reacts with excess BaCl2. If the sample produces 0.530 g of BaSO4, what is the mass percent of Al2(SO4)3 in the sample?
*March 20, 2013 by edi*

**Chem**

A 0.2181 g sample of KHP required 17.29 mL of sodium hydroxide solution to reach the phenolphthalein end point. Calculate the molarity(M) of the NaOH solution.
*October 9, 2012 by Donnie*

**statistics**

Assume we draw a simple random sample from a population having a mean of 100 and a standard deviation of 16. What is the probability that a sample mean will be within plus-or-minus two of the population mean for each of the following sample sizes? (a.) n = 50 ____________ (b...
*December 2, 2009 by Desire*

**statistics**

if the null hypothesis is that the mean is 3218, the alternative hypothesis is that the mean > 3228, and the sample mean is x= 3342, the sample standard deviation is s=287, the sample size is n= 42, and α= 0.01 a. calculate the z test statistic. b. what is the p-value...
*April 29, 2012 by emily*

**Chemistry **

Sodium hypochlorite, NaClO, is added as a disinfectant to the water supply. You are analyzing a sample from the supplier to verify its purity and you prepare to titrate 250.0 mL of a solution containing 1.86 g of NaClO with a 1.00 M HCl solution. What is the pH of the solution...
*February 13, 2012 by Rosa*

**Chemistry**

Can anyone just show me the steps and point me in the right direction??? A sample of oxygen gas has a volume of 8.00 L at 20.0 ° C and 700. torr. How many moles does the sample contain?
*December 1, 2010 by Anonymous*

**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*

**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**

What is the probability that we would obtain two sample means that differ by 1.875, when the SD of the sampling distribution is estimated at .125 when our sample has 8 subjects?
*October 7, 2012 by nina*

**chemisty**

a 10.00ml diluted chloride sample required 44.89 ml of 0.01982 m abno3 to reach the fajans end point. how many moles of cl ion were present in the sample
*October 25, 2012 by lisa*

**chemistry**

if 53.0mL of 0.150M of HCl is needed to neutralize all the NH3 from a 2.28g sample of organic material. what is the mass percent of notrogen in the sample?
*November 1, 2012 by lisa mendez*

**ap chemistry**

A sample of gas occupies 4 mL at STP. At what pressure would this sample occupy 500 mL if the temperature is changed to 525C? Answer in units of torr
*February 9, 2013 by cheri*

**Physics**

The activity of a sample of 35(upper#) 16(lower#)Sulfer (T 1/2= 7.55x10^6 s) is 2.51x10^5 decays per second. WHat is the mass of the sample? m= in grams PLease help me out...Thank you! :)
*May 7, 2013 by Leila*

**Physics!**

The activity of a sample of 35(upper#) 16(lower#)Sulfer (T 1/2= 7.55x10^6 s) is 2.51x10^5 decays per second. WHat is the mass of the sample? m= in grams PLease help me out...Thank you! :)
*May 8, 2013 by Leila*

**Chemistry**

A 3.000gram sample of a hydrate compound containing Co, C2O4, and H2O was combusted to give 1.316g of Co3O4. What is the percentage of Cobalt in the original sample?
*June 6, 2013 by Jessica*

**statistics**

The Democrat and Chronicle reported that 25% of the flights arriving at the San Diego airport during the first five months of 2001 were late (Democrat and Chronicle, July 23, 2001). Assume the population proportion is p = .25. 1. Calculate () with a sample size of 1,200 ...
*October 19, 2009 by jessica knowes*

**statistics**

A sample of n = 5 scores has a mean of M = 12. What is ‡” x for this sample?
*May 28, 2011 by Dottie*

**chemistry**

there's a 5.44 g sample of NH4NO3 and 150 g sample of water. So they ask for the change in enthalpy in kJ/mol. They give the temperature change from 16.2 degrees C to 18.6 degrees C. They also provide the specific heat capacity of the entire solution (155.4g) as 4.2 J/g*K. How...
*October 20, 2009 by anna*

**chemistry**

there's a 5.44 g sample of NH4NO3 and 150 g sample of water. So they ask for the change in enthalpy in kJ/mol. They give the temperature change from 16.2 degrees C to 18.6 degrees C. They also provide the specific heat capacity of the entire solution (155.4g) as 4.2 J/g*K. How...
*October 21, 2009 by anna*

**chemistry**

A 32.0-g sample of water at 290. K is mixed with 51.0 g water at 310. K. Calculate the final temperature of the mixture assuming no heat loss to the surroundings.
*April 21, 2013 by David*

**Analytical chemistry**

I did the next problem, i don't have the results for it and i just want to know if i calculated the mass for Fe2O3 the right? A sample is a mixture of iron oxides (Fe2O3 and FeOOH). It's known that at 200°C this reaction occurs: 2FeOOH(s)-> Fe2O3(s) + H2O(g) A 0.2564g ...
*September 7, 2013 by Gloria*

**statistics**

A sample of purchases at the local convenience store has resulted in the following sample data, where x = the number of items purchased per customer and f = the number of customers. x= 1,2,3,4,5 f=8, 20, 8, 8, 7 What does the 20 stand for in the above table? Find the midrange ...
*September 29, 2012 by Anonymous*

**Statistics**

For sample mean x = 150, sample size n = 36 and sample standard deviation s = 40 find 80% confidence interval for population mean. Population standard deviation is not known
*February 24, 2012 by Tina*

**Statistic **

consider the population of all students at your school. A certain portion support mandatory national service following high school. Your friend randomly sampled 20 students from the school, and uses the sample proportion who support MNS to predict the population at the school...
*September 11, 2012 by Anonymous*

**Physics**

If a sample of a radioactive isotope has a half-life of 5 year(s), how much of the original sample will be left at the end of the second year? How much will be left at the end of the third year of thr original sample? How much will be left at the end of the fourth year of the ...
*November 23, 2009 by TITA*

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