# Posts by JJ

Total # Posts: 1,048

**chemistry**

What is the osmotic pressure, expressed in the unit mmH2O, of a solution containing 125 ug of vitamin B12 (C63H88CoN14O14P) in 2.50 mL H2O at 25 degrees C? Answer: 9.33 mmH2O

*February 25, 2013*

**Chemistry: Freezing point**

An aqueous solution is prepared by dissolving 1.08 g of human serum albumin, a protein obtained from blood plasma, in 50.0 mL of water. The solution has an osmotic pressure of 0.00770 atm at 298 K. What is the molar mass of the albumin? Answer: 6.86 x 10^4 g/mol

*February 25, 2013*

**Chemistry**

A crystalline white solid is a mixture of glucose (C6H12O6) and sucrose (C12H22O11). Is it possible that a 10.00 g sample of the solid dissolved in 100.0 g H2O might have a freezing point of -1.25 degrees C? Explain. Answer: No. The freezing point would be -1.03 degrees C

*February 25, 2013*

**Chemistry**

A 1.065-g sample of an unknown substance is dissolved in 30.00 g of benzene; the freezing point of the solution is 4.25 degrees C. The compound is 50.69% C, 4.23% H, and 45.08% O by mass. Info you might need on benzene: Normal Freezing point,degrees C: 5.53 Kf, degrees m^1: 5....

*February 25, 2013*

**Chemistry**

What mass of sucrose, C12H22O11, should be added to 75.0 g H2O to raise the boiling point to 100.35 degrees C? Molal boiling point of water: 0.512 Kb, degrees C m^-1 Answer: 18 g sucrose

*February 25, 2013*

**chm**

Why are the atomic masses listed in the periodic table not whole numbers? Answer Scientists have yet to make the precise measurements. That would be too much of a coincidence. ??>>The atomic masses are average atomic masses. or >>Today's instruments are able to...

*February 23, 2013*

**chm**

How would you classify the following material?swimming pool water homogeneous mixture<<< heterogeneous mixture a pure element a pure compound depends on how many children have been in it

*February 23, 2013*

**algebra 1**

If it is 1/(a-y) = 1/y then cross multiply to get y = a -y solve for y in terms of a.

*February 22, 2013*

**Math**

pace is 400 meters/48 seconds You could use a proportion; 400/48 = x/192

*February 22, 2013*

**Math -algerbra**

Are you just taking the square root of the x? If so: x - square root of x = 12 or is it x = sqrt(x+10) + 2? if so: x -sqrt(x+10) = 2 Square both sides: Then solve.

*February 22, 2013*

**math**

It means when y = 0 then x = 1 0 = 1^2 + b(1) + 1 0 = 1 + b + 1 Solve for b.

*February 22, 2013*

**Algebra 1**

3n - 4n -4 = 1/3(n+4) -n - 4 = 1/3 (n+4) multiply all parts by 3 -3n -12 = n + 4 -4n = 16 n = -4

*February 22, 2013*

**Chemistry**

4.0 g/1mole = .54 g/x mole This is a proportion. Cross multiply to find the answer

*February 22, 2013*

**Please help on geometry - analytic geometry**

It helps if you plot the points first, then you can find the length of the sides of the triangle. area of a triangle is 1/2 base times height.

*February 22, 2013*

**Algebra 1**

That isn't the answer. That was just an example of what consecutive even numbers mean to show why we are using n, n+2 and n+4. My equation is the same as yours.

*February 22, 2013*

**Algebra 1**

Even numbers have a differnce of two. 2, 6, and 8 are consecutive even numbers. Let n = 1st Let n + 2 = 2nd Let n + 4 = 3rd 3(n) - 2(2n+2) = 1/3(n+4) Here is the equation. Can you solve it?

*February 22, 2013*

**Math**

l + 2w = perimeter l + 2w = 24 l = 24-2w Area = l times w (24-2w)w = Area. 24w -2w^2 = Area. If you are doing this using calculus, you would take the derivative of the area and set it equal to zero to find w.

*February 22, 2013*

**Guidance and Discipline**

What are the choices?

*February 22, 2013*

**math**

x = the number you start with after round 1: you have x/2 1/3 of those are eliminated which means 2/3 remain Multiply x/2 times 2/3 = x/3 Next round 1/4 are eliminated which means that 3/4 remain. 3/4 times x/3 = x/4 Can you finish from here with rounds 5 and 6 it should end ...

*February 22, 2013*

**Math**

x = 1st number and y = second number 2x + y = 24 2x - y = 12 Can you finish from here? Add the two equations to eliminate y and solve for x. Then find y. Be sure to check both x and y in both equations to be sure you are correct.

*February 22, 2013*

**math**

There are 100 students... and 40 boys. What is the probability of getting a boy? Student wears eye glasses. It looks like 40 wear eye glasses so 40/100 again. I am not sure if the question is two separate problems or they are trying to say .. if you picked a boy and that he ...

*February 22, 2013*

**graphing**

I put the numbers in using the stat function of the TI-83. I hit STAT and edit to put in the numbers in L1 and L2. Then I did Stat -Calc and I chose Quadreg and L1 L2 from keyboard and enter.

*February 22, 2013*

**graphing**

I am taking a chance at this one. See if you agree or not. (0,0) is the initial starting point (55, 0) is the ending point 24.8 is the max height which occurs 1/2 between 0 and 55 so that gives us another point (27.5, 24.8) I used the quadratic regression on the graphing ...

*February 22, 2013*

**HISTORY**

Try a google search. I don't see any history tutors online right now. If you can't find anything repost.

*February 22, 2013*

**Math**

Yes!!

*February 22, 2013*

**Math**

You need to multiply all of the exponents by the 1/4 write 81 and 3^4 first then multiply the 4 times 1/4 =1 so you just have 3^1 which is 3. Now, can you do a and b?

*February 22, 2013*

**math**

L = 3+ 2W see how I created this equation from the first sentence? 77 = LW I will write this by substituting for L 77 = (3+2w)w 77 = 3w + 2w^2 You want to write this in the form of ax^2 + bx + c= 0 because that will allow you to factor and find the width. You will get two ...

*February 22, 2013*

**math**

this value is given to the nearest cent. To round to the nearest tenth or ten cent would be 114.30 to round to the nearest cent.. I would need something like 114.291 that would round to 114.29

*February 22, 2013*

**history**

I bet you could find this in a google search. I don't see a history person online right now. I might guess Mao.

*February 22, 2013*

**Math 0098**

See if you can do this one. It is the same idea as what I just helped you with. Work it out and I will be happy to check your answer.

*February 22, 2013*

**math**

for C. In 1990, the house is worth 94,000 to double it has to be worth 188,000 Putin 188,00 for P(t) then divide both sides by 94,000. That will give you 2= e^.03t take the ln of both sides then solve for t. Are you in calculus? If so.. for B. I would take the derivative that ...

*February 22, 2013*

**math**

15uvw^8 + 30u^5w^9 First you find the GCF. Can you do that with the hints I gave you in the previous question? 15uw is what I think. do you agree? Once you have the GCF. You divide both parts by it (15uw)(vw^7 + 2u^4w^8) Can you do the other two? I will be happy to check your ...

*February 22, 2013*

**math**

What is the biggest number that will go into both 18 and 30? Is it 6? the greatest common factor for variables with exponents is the variable with the smallest power. for the u's the gcf would be u^2 for v^5 none because the second expression doesn't have a v. for the ...

*February 22, 2013*

**Math**

7x + 29 is correct in the numerator. the denominator will be x^2 + 3x - 10 Your mistake is that you added the denominators. You have to keep the denominator and add the numerators when working with fractions. Like 1/5 + 2/5 = 3/5 this is the same denominator that you have on ...

*February 22, 2013*

**Math**

Do you mean 5/(x-2) plus 2/(x+5) = 4/(x^2 + 3x -10) To do this you either need a common denominator or to clear denominators. I have to check the factors of the denomonators. (x^2 + 3x -10) factors to (x+5)(x-2) 5/(x-2) needs to be multiplied by (x+5)/(x+5) 2/(x+5) needs to be...

*February 22, 2013*

**non permissable values**

Nonpermissiable values. You only have to worry about the denominators. A denominator can never be equal to zero since division by zero is not defined. If a denominator is x + 2 , we don't want it to equal zero. So, x cannot = -2 sind that will cause the denominator to ...

*February 22, 2013*

**math**

round 1 you start with x and 1/2 are eliminated (x/2) times 1/3 for what is left after round 2. (x/6)times 1/5 times 1/6 Do the math and then set x/? = 10 solve for x.

*February 22, 2013*

**Math 0098**

-7x -7y =70000 7x + 9y =86000 2y = 156000 divide by 2 and you get 7800 for y so the other amount must be 2200.

*February 22, 2013*

**Math 0098**

Sorry.. the .08 is a typo. It should be .09 Which makes the equation 7x + 9y = 86000

*February 22, 2013*

**Math 0098**

x = amount in the first account y = amount in the second account. total invested: x + y = 10,000 since Interest = Principles times rate times time. .07x + .08y = 860 Now, you work with those two equations. I would multiply the bottom equation by 100 to get rid of the decimals...

*February 22, 2013*

**Math 0098**

Do you have numbers for this problem?

*February 22, 2013*

**Calculus**

The derivative of a product. The rule is: the first times the derivative of the second PLUS the second times the derivative of the first. simplify your answer. The derivative of the first: 4x-2 The derivative of the second -3x^-4 -8x^-5 Can you finish with these hints?

*February 22, 2013*

**Algebra II**

Use the slope formula. m = (x2-x1)/(y2-y1) 2 = (2 -1)/(y-3) Multiply (y-3) times each side of the equation. Simplify and solve for y.

*February 22, 2013*

**math**

n = ist number n+1 = second number the sum: n + n + 1 or 2n + 1 reciprocal we would want 1/(2n+1) and that should equal 11/30 Set the two fractions equal to each other Cross multiply and then solve for n. then find n+1

*February 22, 2013*

**math**

12/60 = 1/5 of an hour 1 tank can be filled in 1/5 of an hour your rate is 5 tanks per hour 20/60 = 1/3 of an hour The tank can be filled in 1/3 of an hour. your rate is 3 tanks per hour (5 tanks per hour)time + (3 tanks per hour)time = 1 tank filled 5t + 3t = 1 t =1/8 of an ...

*February 22, 2013*

**Calculus**

This is derivative of a division (fraction. the rule is the denominator times the derivative of the numerator - the numerator times the derivative of the denominator. ALL OVER the denominator squared. The denominator of the derivative is the easy part. It is just (t^4 -2)^2 ...

*February 22, 2013*

**Math**

a. equal number of each Combinations again.. architects 4!/(2!2!) engineers 6!/(2!4!) electricians 9!/(2!7!) b. remove the 2 engineers from the choices which would leave 4 architechts, 4 engineers and 9 electricians Now, we have 17 to choose from to make a group of 6. 17!/(6! ...

*February 22, 2013*

**Math**

Remember an odd number has to end with 1, 3, 5, 7, or 9 An even number is divisible by 2 and has to end in 0, 2, 4, 6, or 8

*February 22, 2013*

**Math ASAP**

24 is the original perimeter. P = 2l + 2w Just wanted to add that information. You could also just multiply the 24 times 1.5 to get the new perimeter of 36 and then take the difference. The math is a little easier.

*February 22, 2013*

**Math**

This is a combination Do you know that 5! = 5x4x3x2x1 =120?? from the 10 people you will choose 7 10! divided by (7!3!) Once you have your group of 7 then there are only 3 people left to put into the group of 3. That is only 1 way. I think the answer is 4320 ways. for 3 groups...

*February 22, 2013*

**Math**

I think you are asking for the sum of a series. You are starting with 2 and there is a difference of 3. There is a formula to calculate this total and it won't be 77.

*February 22, 2013*

**Chemistry**

Supersaturated solutions are unstable because they are holding more solute than is normally possible. All it takes is for a tiny bit to be added and it begins to crystallize. If you think of a normal salt/water solution. You can get just so much salt to dissolve in water at a ...

*February 22, 2013*

**math**

I am assuming that you want to reduce the height proportionally to reducing the width. You made the width 1/2 as big when you took it from 6" to 3 ". You divided 6 by 2 to get 3. What do you think you should do to the 14"?

*February 22, 2013*

**math**

4/16 getting a red the first time No replacement 3/15 getting a red the second time Multiply these probabilities together.

*February 22, 2013*

**physics**

100/9.86 with give you his velocity running. 100/90.9 will give you his velocity walking. Average the two to get his average velocity in m/sec for the 200 m.

*February 22, 2013*

**statistics**

You are looking for the area under a normal curve between -1.5 and 1.5 standard deviations. Use a calculator to find this area or Use a z-table.

*February 22, 2013*

**US HISTORY**

WHAT HAPPENED AT THE CVITY OF GONZALES

*February 21, 2013*

**US HISTORY**

Do a google search of the ALAMO

*February 21, 2013*

**US HISTORY**

WHAT PROBLEMS DID THE AMERICANS AND THE MEXICANS HAVE WITH EACH OTHER IN TEXAS

*February 21, 2013*

**US HSITORY**

HOW DID MEXICAN INDEPENDENCE CHANGE TEXAS

*February 21, 2013*

**Composition**

You need to write your revision and then someone here will check it for you.

*February 21, 2013*

**statistics**

We need to know some other information. Like the mean and standard deviation for these scores. subtract the mean from 37.5 and divide by the standard deviation to get a z-score. do the same for 39. Use a z-table to find the percentage of scores that will be between the two ...

*February 21, 2013*

**math**

5/97 divide 5 by 97 to get a decimal answer. Then move the decimal point two places to ther right and include a % sign.

*February 21, 2013*

**math**

You have to know how many pints in a quart. 4 cups in a quart - Right? would there be 2 pints in a quart? If so, multiply that number times the quarts to get number of pints then you can add up the 3 values.

*February 21, 2013*

**math**

So.. is A times 0.25 = B If so, then A = 56/0.25 or is A/B = 0.25 If so, then A = B times 0.25 which gives us A = 56 times 0.25

*February 21, 2013*

**Math**

I am getting x^2+2x+9 with no remainder Did you divide x - 2 intot x^3 + 0x^2 + 5x -18 You need to put in the 0x^2 because you have the missing x^2 term. since you are dividing by x-2 we cannot have x-2 =0 because division by zero is undefined. So.. we would not want x to be 2...

*February 21, 2013*

**physics**

Kinetic Energy = 1/2 times m v^2 1.00 x 10^-19 = (1/2)(1.673x10^-27)v^2 solve for v^2 then take the square root to get v.

*February 21, 2013*

**Math**

You need to get common denominators. (9)(8(7) will be the common denominator. multipy the numerator of the 7/9 fraction by (8)(6) and multily the denominator by the same thing. do something similar to the other 2 fractions then compare their numerators.

*February 21, 2013*

**Math**

Find out how many degrees is in each slice. Divide that answer into 360 which is the number of degrees in the circle and then you will find the number of slices. You could set up a proportion: 72/3 = 360/?

*February 21, 2013*

**Algebra**

factor a 2 out of the 2y-4 in the numerator. then you can cancel out like factors. Can you finish from here?

*February 21, 2013*

**MATH**

No.. they said he makes $7 per day.

*February 21, 2013*

**MATH**

This seems a little odd to me. if he is paid $7 per day and works 5 days, he should make $35. Is something missing from the question or is this a question where they want you to ignore the extra information?

*February 21, 2013*

**Science**

Yes, it is b. the other are between the same elements so those are nonpolar covalent.

*February 21, 2013*

**Math**

A circle has 360 degrees for 18 parts divide 360 by 18 for 5 parts divide 360/5

*February 21, 2013*

**Math**

50.00 - $18.42 That will tell us how much more he has to earn. Then you would divide this by 2 to get the amount per week.

*February 21, 2013*

**math**

I just answered to on of your earlier posts. Check it out.

*February 21, 2013*

**math**

120 cards per drawer and 2/3 are baseball. He has 240/3 = 80 baseball cards per drawer. He actually has 240 baseball cards right? because he has 3 drawers. He will trade 1/4 of the 240 = Can you finish it?

*February 21, 2013*

**geometry**

Perpendiculars form right angles which are = to 90 degrees.

*February 21, 2013*

**math**

2/8 + 3/8 = 5/8 these are pink and white. How many are purple? 8/8 - 5/8 = ?

*February 21, 2013*

**math**

1/4 of the t-shirts are pink There are 3/4 of the shirts remaining. 1/2 of these 3/4 are white. so we multiply to get 3/8 the rest are purple. we know 1/4 are pink and 3/8 are white. Get a common denominator and add these two fractions and then subtract from 1 which can be ...

*February 21, 2013*

**math**

It is math that you do in your head without paper or pencil or a calculator.

*February 21, 2013*

**math**

x y 4 -1 5 -2 6 -3 7 -4 The rule seems to be as x increases by 1, y decreases by 1

*February 21, 2013*

**Math Gr.12 (Calculus)**

What are you doing with it? Are you trying to solve for x? If so, you have to subtract 3 from both sides so one side = 0 0 = 6x^2 -2x - 11 If this won't factor, you can use the quadratic equation to solve for x. -b +/- (the square root of (b^2-4ac)) all of this divided be 2a.

*February 21, 2013*

**MATH**

9x^2 + 5x - 4 the AC method Multiply the 9 times -4 You have -36 think of factors that will multiple to equal -36 but add to equal the middle number 5. 36 times -1 no 9 times -4 yes Sometimes it takes awhile to find the right numbers. Once you do, you write them and -4x + 9x ...

*February 21, 2013*

**MATH**

y^3 + y^2 - 4y - 4 factor by grouping the first two and the last two. Be careful with the second grouping because of the _(-) in front of the 4y. (y^3 +y^2) + (-4y -4) Take out the common factors: y^2(y+1) + -4(y+1) See the y+1? Write that down once and your other factor is ...

*February 21, 2013*

**math**

Did they ask how much would they sell the ice for? or what is the profit? the profit is $225 and the total price they will sellit for is $975 Read the question again carefully.

*February 21, 2013*

**math**

$225 is the profit. they will sell the ice for $750 + 225 which is $975 total.

*February 21, 2013*

**math**

Did you read my answer to her questions? We start by dividing 1500 by 5 lbs per bag to get the number of bags which is 300 Since each bag costs 2.50 and we have 300 of them. we paid how much? Once you get that answer multiply by 30% or .30 to get the profit.

*February 21, 2013*

**math**

It is Megan... write below us.

*February 21, 2013*

**math**

If you look before this note. You will see your problem listed below. If you don't see it let me know and I will do it again.

*February 21, 2013*

**math**

I did answer this one earlier.

*February 21, 2013*

**math**

A circle has 360 degrees. The angle for each slice should be 36 degrees. Can you figure out the angle for 3 slices?

*February 21, 2013*

**math**

Okay.. just think about it a little more.

*February 21, 2013*

**math**

1500 divided by 5 = 300 You wrote that step backwards. 300 X 2.50 = 750 Why did you subtract 120 and 36?? that isn't needed? Multiply 750 x .3 is correct $225 is the answer. What part is confusing. if you have 1500 lbs and each bag weighs 5 lbs. YOU must have 300 lbs. ...

*February 21, 2013*

**math**

It costs $2.50 per bag and you have 300 bags. You have to multiply them. Does that make sense?

*February 21, 2013*

**math**

5 lbs per bag... How bags will you have? 1500/5 = 300 bags how much does she pay for the 300 bags? Can you do this step? If so, the next step is just multiplying that answer by .3 to find the profit.

*February 21, 2013*

**trig**

tan x = opposite/adjacent cot x = adjacent/opposite they are reciprocals of each other. tan x = 1/cot x Can you finish from here?

*February 21, 2013*

**Algebra**

You are welcome.

*February 21, 2013*

**Algebra**

56/(56+x) = 70/100 silver/(silver + additive) silver / total weight is 70% or 70/100 56/(56+x) = .7 Cross multiply and solve for x

*February 21, 2013*