Friday

February 27, 2015

February 27, 2015

Total # Posts: 351

**Statistics **

With a known population mean of 100, and a known standard of error of the mean of 7.5, what is the probability of selecting at random a sample whose mean is equal to 110 or greater?
*February 27, 2015*

**Algebra**

I need some help with this question I really don't understand it and some help going through this problem would be really appreciated :) Use the fact that a/b/c/d=a/b / c/d to simplify each rational expression. State any restrictions on the variables. x^2-1/x^2-9 / x^2+3x-...
*February 27, 2015*

**Math **

Explain how to solve the following system of equations. What is the solution to the system? 2x+2y+z=-5 3x+4y+2z=0 x+3y+2z=1
*January 21, 2015*

**Math**

Would the answer be c?
*January 21, 2015*

**Math**

Every year in Delaware there is a contest where people create cannons and catapults designed to launch pumpkins as far in the air as possible. the equation y=15+110x-16x^2 can be used to represent the height, y, of a launched pumpkin, where x is the time in seconds that the ...
*January 21, 2015*

**math**

At a given time, Saturn was 9.1 x 10 to the 8th miles from the sun and the earth was 9.3 x 10 to the 7th miles from the sun. by what distance is one planet closer to the sun than the other planets?
*January 14, 2015*

**PHYSICS**

A uniform plank with mass 20kg and length 12m extends 2m over the edge of a building. A 40kg crate is slid out on the plank. how far can the crate be pushed without toppling the plank? A. 0.5m B. 1m C. 1.25m D. 1.5m E. 2m
*January 4, 2015*

**Physics**

A 3kg mass is sliding across a horizontal surface at a constant speed while being pulled by rope with tension 20N held at a 53 degree angle above the horizontal. The force of friction is most nearly A. 30N B. 12N C. 16N D. 20N E. 1N
*January 4, 2015*

**Struggling in Writing**

Thank you for your optimism! After reading your posts, I felt more encouraged and more motivated to try my best. Have a wonderful day! :) Writing well will be my goal!
*December 4, 2014*

**Struggling in Writing**

Should I be ashamed for being a poor writer and reader,since I am in 12 th grade this year? Today,in writing class I struggled.. I could not identify the thesis of an article nor could I spot counterclaim that the author makes. I think I have dyslexia because I have a hard ...
*December 4, 2014*

**8th grade English/Language Arts**

Thank you Ms.Sue. You are very great with this homework helping are you the coordinator
*October 28, 2014*

**8th grade English/Language Arts**

Okay, please help me with the rest
*October 28, 2014*

**8th grade English/Language Arts**

1.)Why does the author of “Always to Remember” discuss Maya Ying Lin’s background? a.)to show that she experienced hardships b.)to appeal to Chinese-American readers c.)to show its influence on her design d.)to show her disinterest in architecture 2.) Which of ...
*October 28, 2014*

**8th grade; English**

Can someone post the answers I am tutoring my brother with english and i need some work problem i think this is a good work examples.. answer asap
*October 25, 2014*

**statisitcs **

The combined math and verbal scores for students taking a national standardized examination for college admission is normally distributed with a mean of 560 and a standard deviation of 180. If a college requires a student to be in the top 40 % of students taking this test, ...
*October 23, 2014*

**Science**

They were wrong because it said that in my book but thank you so much
*September 29, 2014*

**Science**

May you please tell me if these are true or false, if they are false then can I have the true statement, thank you In the water cycle, water returns to Earth as (condensation) usually in the form of rain or snow During dry weather, the water level in a small pond drops because...
*September 29, 2014*

**math**

I thought that you had to cross off the two zero's from each side.That is what my teacher has told me.
*September 25, 2014*

**math**

Yes it could be simplified to 5/9.
*September 25, 2014*

**MATH**

A HUMMINGBIRD BEATS IT WINGS 53X SEC HOW MANY TIMES DOES THE HUMMINGBIRD BEATS IN 5 SEC
*September 11, 2014*

**Science**

Why are aboriginal clan systems considered human social systems?
*September 6, 2014*

**English**

Start with your interests like. Fore say you like the arts. Explain how you feel about it. The begging should always be different that the others. Something unique about yourself. Of course you can also start saying what is you name. Bot it's your call
*September 6, 2014*

**AP Physics **

Two locomotives approach each other on parallel tracks. Each has a speed of v = 85 km/h with respect to the ground. If they are initially d = 7.0 km apart, how long will it be before they reach each other?
*September 5, 2014*

**AP Physics **

A car traveling 92 km/h is 130 m behind a truck traveling 75 km/h. How long will it take the car to reach the truck?
*September 5, 2014*

**Pre Cal**

Two forces with magnitudes of 100 and 50 pounds act on an object at angles of 50° and 160° respectively. Find the direction and magnitude of the resultant force. Round to two decimal places in all intermediate steps and in your final answer.
*August 5, 2014*

**chemistry**

When 3.00 moles of sodium are reacted with large amounts of chlorine gas 145.8 g of sodium chloride are produced determine percentage yield
*July 16, 2014*

**Finacial Accounting.**

I am really struggling with this question and my accounting book is no help at all. A company has $4500 in net sales, $3200 in gross profit, $1300 in ending inventory, and $1800 in beginning inventory. What is the cost of goods sold? Im not looking for the answer, just a ...
*June 29, 2014*

**Chemistry**

A solution buffered at a pH of 5.00 is needed in an experiment. Can we use acetic acid and sodium acetate to make it? If so, how many moles of NaC2H3O2 must be added to a 1.0L of a solution that contains 1.0 mol HC2H3O2 to prepare the buffer. The Ka of acetic acid is 1.8x10^-5...
*June 20, 2014*

**Chemistry**

Determine the concentration of CO32- ions in a 0.18 M H2CO3 solution. Carbonic acid is a diprotic acid whose Ka1 = 4.3 × 10-7 and Ka2 = 5.6 × 10-11.
*June 18, 2014*

**Chemisty**

A 0.411 g sample of powdered copper mixed with an inert, soluble additive was fully consumed by 23.4mL of 0.602M nitric acid, producing copper (II) nitrate, water, and nitric oxide. What is the percent copper by mass in the sample? 3Cu + 8HNO3 = 3Cu(NO3)2 +2NO =4H2O
*June 17, 2014*

**Chemistry**

what is the pH solution in which 15 mL of 0.10 M NaOH has been added to 25 mL of 0.10 M HCl
*June 10, 2014*

**Chemistry**

the answer is 0.75mol SO2 but I don't understand where to even begin
*June 9, 2014*

**Chemistry**

Consider the following equilibrium. 2 SO2 (g) + O2 (g) 2 SO3 (g) The equilibrium cannot be established when __________ is/are placed in a 1.0-L container.
*June 9, 2014*

**Chemistry**

what volume (mL) of 0.0962M NaOH is required to neutralize 10.0mL of 0.128M H2SO4? I got 26.6mL
*June 8, 2014*

**algebra**

4x^3-6.68E-7x^2+1.67E-8x-1.04E-10 = 0
*June 8, 2014*

**Math**

4x^3-6.68E-7x^2+1.67E-8x-1.04E-10 = 0
*June 8, 2014*

**Chemistry**

I posted this last night, A 0.500L vessel initially contains 0.0125 mol of H2S2 . Find the equilibrium concentrations of H2 and S2. Kc = 1.67 x 10^-7 2 H2S <--> 2 H2 + S2 I have come up with this equation so far, but I am lost now because I don’t even know if this ...
*June 8, 2014*

**Chemistry**

How many grams of pure H2SO4 can be obtained from 250 grams of iron ore if the ore is 82% FeS2? The reactions involved are given below: 4FeS2 + 11 O2 --> 2 Fe2O3 + 8 SO2 (95% efficient) 2SO2 + O2 --> 2SO3 (90% efficient) SO3 + H2O --> H2SO4 (90% efficient)
*June 7, 2014*

**Chemistry**

I got this equation but now I am lost 1.67x10^-7 = ((4x^2)(x)) / (0.000625-4x^2)
*June 7, 2014*

**Chemistry**

A 0.500L vessel initially contains 0.0125 mol of H2S2 . Find the equilibrium concentrations of H2 and S2. Kc = 1.67 x 10^-7 2 H2S <--> 2 H2 + S2
*June 7, 2014*

**Chemistry **

I posted this question before and the answer is suppose to be 6.8 L but I keep getting 6.12 L dinitrogen pentoxide n2o5 decomposes by a first-order decomposition in chloroform solvent to yield NO2 and O2. The rate constant at 45°C is 6.2 x 10^-4 mins^-1. Calculate the ...
*June 3, 2014*

**Chemistry**

I keep getting 6.12 and the answer is suppose to be 6.8
*June 3, 2014*

**Chemistry**

dinitrogen pentoxide n2o5 decomposes by a first-order decomposition in chloroform solvent to yield NO2 and O2. The rate constant at 45°C is 6.2 x 10^-4 mins^-1. Calculate the volume of O2 obtained from the reaction of 1.00 mol N2O5 at 45°C and 770 mmHg after 20.0 hours...
*June 3, 2014*

**Chemistry**

Or this balanced equation actually N2O5 = 2 NO2 + 1/2 O2
*June 3, 2014*

**Chemistry**

dinitrogen pentoxide n2o5 decomposes by a first-order decomposition in chloroform solvent to yield NO2 and O2. The rate constant at 45°C is 6.2 x 10^-4 mins^-1. Calculate the volume of O2 obtained from the reaction of 1.00 mol N2O5 at 45°C and 770 mmHg after 20.0 hours...
*June 3, 2014*

**Chemistry**

Nevermind I got the answer myself!
*June 3, 2014*

**Chemistry**

The potassium salt of benzoic acid, potassium benzoate, KC7H5O2, can be made by the action of potassium permanganate on toluene, C7H8. C7H8 + 2 KMnO4 --> 2MnO2 + KOH + H2O If the yield of potassium benzoate cannot be realistically be expected to be more than 71%, what is ...
*June 3, 2014*

**Chemistry **

The first order rate constant is 1.87 x 10^-3 min^-1 at 37°C for reaction of cisplatin. Suppose the concentration of cisplatin in the bloodstream of a patient is 4.73 x 10^-4 mol/L. Calculate the concentration exactly 24 hours later.
*June 3, 2014*

**Chemistry**

How many grams of commercial C2H4O2 (97% pure by mass) must be allowed to react with an excess of PCl3 to produce 50.0g of C2H3OCL if the reaction has a 70% yield? 3C2H4O2 + PCl = 3C2H3OCl + H3PO4
*June 2, 2014*

**Chemistry**

I actually was able to figure it out
*May 31, 2014*

**Chemistry**

0.135m
*May 31, 2014*

**Chemistry**

How many moles of KF are contained in 244 mL of 0.135 m KF solution? The density of the solution is 1.22 g/mL.
*May 31, 2014*

**Chemistry**

At 20°C, an aqueous solution that is 18.0% by mass in ammonium chloride has a density of 1.0512 g/mL What is the molarity of ammonium chloride in the solution?
*May 31, 2014*

**Chemistry**

the solubility of 1-butanol in water is 7.9g per 100g of water. What is the maximum amount of 1-butanol that will dissolve in 5.9g of water
*May 31, 2014*

**Chemistry**

What is the mass percent of an aqueous sodium hydroxide solution in which the molality of NaOH is 6.25m? The density of the solution is 1.2219 g/mL
*May 31, 2014*

**Chemistry**

A sulfuric acid solution that is 65.0% H2SO4 by mass has a density of 1.55 g/mL at 20°C. What is the mass of h2so4 per liter of solution?
*May 31, 2014*

**Chemistry**

Manganese trifluoride, MnF3,can be prepared by the following reaction. 2 MnI2 (s) + 13 F2 (g) ---> 2 MnF3(s) + 4 IF5(l) What is the minimum number of grams of F2 that must be used to react with 12.0 g of MnI2 if the overall yield of MnF3 is no more than 75% of theory?
*May 26, 2014*

**Chemistry**

If 150 mg of aspirin are rinsed with three portions of 10 mL of water at 25 degrees Celsius, how much aspirin is recovered? Solubility of aspirin in water at 25 degrees Celsius is one gram of aspirin per 300 mL of water.
*May 20, 2014*

**Pre-cal**

D) 2log10+log1000-log1
*May 14, 2014*

**Pre-cal**

Simplify: A) log(x+1)+3logx B) 2log4np-3log4p C) 2ln(3x)+ln(5x)-ln6xy D) 22log10+log1000-log1
*May 14, 2014*

**Pre - Cal**

1. Find the vertex of the parabola: 4y^2+4y-16x=0 2. Find an equation of the parabola, opening down, with vertex (-3,1) and solution point (4,-5). 3. The main cables of a suspension bridge are 20 meters above the road at the towers and 4 meters above the road at the center. ...
*May 5, 2014*

**physics**

a rod is having a positive charge and a point charge is placed at a distance 'd' from it making angle 45 degree with one end and 37 degree with the other.calculate field. plz answer its urgent.
*April 10, 2014*

**chemistry **

How many grams of magnesium are required to produce a total of 4.05g of hydrogen
*April 2, 2014*

**Physics**

Prove that tanø is equal to U(k) when the block slides down the incline with a constant speed. (Use symbols, not numbers.)
*March 19, 2014*

**science**

foxes eating mice or leaves growing on trees or rabbits easting clover or fleas living on cat
*February 17, 2014*

**science**

a consumer-producer relationship is best illustrated
*February 17, 2014*

**scince**

as you drive down the highway you may see crows feeding on dead animals. as a result of this nutritional pattern,crows may be classified as
*February 17, 2014*

**chemistry**

solve net ionic equATION Ba(OH)2 + Na2SO4
*February 13, 2014*

**Math**

A swing has a maximum height of 2 m and a minimum height of 0.5 m and it takes 3 seconds to get from the maximum height to the minimum height. Approximate the instantaneous rate of change 1 second into the fall using the difference quotient when h is 0.01. a)-1.3650 b)-0.1973 ...
*November 29, 2013*

**Chem**

I can't find the value x by calculation. It ends up to give me a quadratic equation and the value of x is negative! please help me ASAP...
*November 8, 2013*

**math 5th grade**

59425
*September 17, 2013*

**chemistry**

How would you prepare 500mL of 6.0M NaOH solution using solid NaOH pallets?
*August 8, 2013*

**Informal logic **

Catherine goes to her local movie theater only to see romantic comedies. Since Catherine did not go to the movies yesterday, there is not a romantic comedy playing at her local theater. The reasoning above is flawed because the evidence does not suggest that Catherine goes to ...
*July 14, 2013*

**Informal logic **

All sages provide both wisdom and inspiration. Since Dasha’s speech contained wisdom and greatly inspired her audience, Dasha is a sage. Which one of the following points out the flaw in the argument above? (Points : 1) -Just because Dasha is a sage doesn’t mean that...
*July 14, 2013*

**chemistry**

to what volume should you dilute 0.100L of a 15M NaOH solution to obtain a 1.0M NaOH solution
*July 10, 2013*

**physics**

scientific interpretation of two toy cars having bar magnet on the roof .what happen when close to each other from same and different direction?
*July 2, 2013*

**Math**

Given the altitude of lakes in feet: –12, –9, –14, –39, –49, –49, –18, –43, find the mean, median, mode, and range
*April 22, 2013*

**chemistry**

A reaction produced 0.40 mmol of H in a buffered solution which contained 300ml of 0.06M succinate buffer, pH is 4. What was the pH of the medium after the reaction was completed? The pKa of succinate buffer is 4.21
*April 19, 2013*

**chemistry**

To what volume should 100ml of any weak acid (HA) with a concentration of 0.2M be diluted to double the percentage ionization?
*April 19, 2013*

**Chemistry **

The of hydroxylamine, , is . A buffer solution is prepared by mixing 120 of a 0.34 hydroxylamine solution with 60 of a 0.25 solution.Solve for the PH
*April 19, 2013*

**Chemistry **

What is the pH of a solution prepared by mixing 25.00 mL of 0.10 M CH3CO2H with 25.00 mL of 0.030 M CH3CO2Na? Assume that the volume of the solutions are additive and that a = 1.8 × 10-5 for CH3CO2H.
*April 19, 2013*

**trig**

Find the first two terms a_1 =5 and an=3a _n-1+2
*March 24, 2013*

**Chemistry**

2Al(s)+3Cl2 = 2AlCl3 Limiting Reactant is Cl with 0.329mol. What is the maximum mass of aluminum chloride that can be formed when reacting 30.0g of aluminum with 35.0g of chlorine?
*February 26, 2013*

**Chemistry**

What is the maximum mass of aluminum chloride that can be formed when reacting 30.0g of aluminum with 35.0g of chlorine
*February 26, 2013*

**statistics**

Suppose a random sample of 80 measurements is selected from a population with a mean of 65 and a variance of 300. Select the pair that is the mean and standard error of x.
*February 26, 2013*

**statistics**

Suppose a random sample of 80 measurements is selected from a population with a mean of 65 and a variance of 300. Select the pair that is the mean and standard error of x.
*February 26, 2013*

**math**

133ft.
*January 21, 2013*

**math**

A 6ft man stands next to a 100ft. tall building. the man's shadow is 8ft. long. How long is the building's shadow?
*January 21, 2013*

**math**

how can i find four equivalent expressions example: 50+225
*December 11, 2012*

**chemistry**

Steve, in an attempt to impress his girlfriend, plops 18.2 grams of sodium metal into 500 mL of concentrated phosphoric acid (density = 1.88 g/cm3) in a beaker. The reactants were both initially at 25 oC. The reaction gently produced bubbles of hydrogen and Janet was not ...
*December 9, 2012*

**Chemis**

Steve, in an attempt to impress his girlfriend, plops 18.2 grams of sodium metal into 500 mL of concentrated phosphoric acid (density = 1.88 g/cm3) in a beaker. The reactants were both initially at 25 oC. The reaction gently produced bubbles of hydrogen and Janet was not ...
*December 9, 2012*

**Chemistry**

Strontium metal is responsible for the red color in fireworks. Fireworks manufacturers use strontium carbonate, which can be produced by combining strontium metal, graphite (C), and oxygen gas. The formation of one mole of SrCO3 releases 1.220 x 103 kJ of energy. a) Write a ...
*December 3, 2012*

**Chemistry**

Compute the ƒ´Hrxn for the following: CH3OH „³ H2CO + H2 Carbon is the central atom on both the starting material and the product.
*December 3, 2012*

**Chemistry**

A hungry backpacker needs to boil 150 mL of water to prepare a cup of Ramen Noodles. The filtered river water is at a temperature of 14.2 oC. The pressure is 760 mm Hg and he wants to eat the chicken flavored noodles. How many mL of his liquid butane camping fuel will he use ...
*December 3, 2012*

**math**

A flagpole casts a 32-ft shadow. A boy who is 6 feet tall is standing near the flagpole casting a 16-ft shadow. They form similar triangles. How tall is the flagpole?
*December 1, 2012*

**Chemistry**

Objectives To determine the molecular weight of a volatile liquid. Discussion [This laboratory exercise was adapted from one in Beran and Brady's Laboratory Manual for General Chemistry , John Wiley & Sons, 1982] The Dumas Method for determining the molecular weight of a ...
*November 27, 2012*

**Chemistry**

A Balloon Time® tank holds 15% excess capacity to fill 50 helium balloons measuring 9” or 0.5 ft3 in volume at 1 atm and 22 oC. The gauge pressure of a new tank is 260 psi. What is the volume of a Balloon Time® tank in ft3?
*October 28, 2012*

**math**

limit (x-9)/(sqrt(x))-3 as x-->9
*September 6, 2012*

**Chem**

1.25 x 10^2
*September 6, 2012*

**physics**

An object is moving at constant velocity of 20m/s for 10 seconds. Find the acceleration during the 10 seconds interval?
*August 25, 2012*