Posts by alex

Total # Posts: 3,726

Chemistry
a 2.00 g sample of C6H402 is burned in a calorimeter whose heat capacity is 8kj/C. The delta T is +7.13 degrees C. What is the enthalpy change per mole?

math
Add all the numbers up but pay attention you are counting 6.30 twice. then you divide by the numbers of days you have.(5) Your answer should be 5.47

math
Arley’s Bakery makes fat-free cookies that cost \$1.60 each. Arley expects 40% of the cookies to fall apart and be discarded. Arley wants a 35% markup on cost and produces 200 cookies. Assume that Arley can sell the broken cookies for \$1.50 each. What should Arley price ...

Pre cal
If Joe invested \$7000 at x% and \$13,000 at 3% more, find x if the income from both investments is \$1190 I'm thinking that the equation would r something like 1,190=(13,000)(.03) but please correct me if I'm wrong. Thank you for your assistance.

MATH
Answer=EGG

MATH
THOSE WERE THE INSTRUCTION(THIS IS THIRD GRADE MATH)

MATH
EACH LETTER IN EACH ADDITION PROBLEM STANDS FOR A NUMBER BETWEEN 0 AND 9.NO TWO LETTERS STAND FOR THE SAME NUMBER IN EACH QUESTION. FIND THE VALUE FOR EACH LETTER.FOR EACH PROBLEM, USE THE NUMBERS IN THE BOX NEXT TO THE PROBLEM. T E N (5,6,1,2,7) + O N _________

Physics
H=5.09684

Algebra
For f(x) = 0.01(2)x, find the average rate of change from x = 2 to x = 10.

math
sally's cell phone company charges a flat rate of \$15.00 per month and \$0.12 per minute. eduardo's cell phone company charges a flat rate of \$18.00 per month and \$0.09 per minute. how many minutes would you have to use for the price to be the same for both plans?

Chemistry
How many grams of solute are required to make a 976 mL solution of sodium hydroxide with a concentration of 0.0783 M?

Linear Algebra - urgent!
A is a diagonalizable matrix. It has the characteristic polynomial det(lambda*I-A)=(lambda-c)^n. Prove that A=cI.

math
florence bought two bags of flour, A and B. the two bags contained different amounts of flour. the total mass was 108 kg. Gary poured 1/4 of the flour from bag A to bag B. After that, he poured 2/5 flour from bag B to bag A. he found that the both bags had the same mass now. ...

math
Distribute the 3, combine like terms, then isolate the variable. -6t + 3t - 6 + 5t = 8 2t - 6 = 8 2t = 14 t = 7

math
Sample mean and population mean are the same for normal distributions.

math
Yes.

Math
Any polygon's total angle can be found by the formula (v - 2) * 180, where v is the number of vertices. In your problem, we have a 7-sided polygon, so v = 7. The total angle is 900. The 6 interior angles of 125 sums to a total of 750, so the seventh, unknown angle is 900...

Linear Algebra
A is a diagonalizable matrix. It has the characteristic polynomial det(lambda*I-A)=(lambda-c)^n. Prove that A=cI.

Chemistry
What is the maximum mass(g) of KCL that can be added to 1.00L of a 0.0100 M lead(ii) chloride solution without causing any precipitation of PbCl2? Assume the additional KCl does not affect the volume of the solution. For, PbCl2, Ksp=1.6x10^-5 Personally I'm at a loss here...

Physics, Math
A helicopter is in a level flight with an altitude of 4000 feet and a speed of 130 feet/sec. The helicopter drop a bomb with 0 speed relative to the helicopter. How far does the bomb travel horizontally from the launch point to impact with the ground?

Calculus - urgent
A lamina. defined by y>=0 with edges y=0, y=3/2(1-x^2) and x=-y+2y^2, for which the density is given by p(x,y)=y. a) define domain as union of type 1 and type 2 region. b) Calculate mass of lamina.

Physics
A 100 kg block is hanging from a frictionless pulley with another block of unknown mass on the other side of the pulley. It is released from a height of 1 meter above the ground. It then takes 0.9 seconds to reach the ground. What is the weight of the other mass? Thanks for ...

Physics
A 100 kg block is hanging from a frictionless pulley with another block of unknown mass on the other side of the pulley. It is released from a height of 1 meter above the ground. It then takes 0.9 seconds to reach the ground. What is the weight of the other mass?

Calculus
The videos did help but i still have trouble setting up the integrals. Since this is part of double integrals section in my course... i'm trying to do it in the form of double integrals. Is this correct? Outer integral is from -pi/2 to pi/2 Inner is [r dr d(theta)] from 3*...

Calculus
A cardioid r=1+cos(theta) A circle r=3*cos(theta) a) Define the domain of the region enclosed inside both the cardioid and the circle. b) Use polar coordinates to calculate the area. (We can use symmetry about x-axis)

Physics
Three objects are connceted by a massless wires over a frictionless pulley. The right side of the pulley wire is connected to a 15kg block and right below that is a 10kg block on the bottom of the wire. The tension in the wire connecting the 10kg and 15kg objects is measured ...

Physics
A 100 kg block is hanging from a frictionless pulley with another block of unknown mass on the other side of the pulley. It is released from a height of 1 meter above the ground. It then takes 0.9 seconds to reach the ground. What is the weight of the other mass?

Physics
Thanks a bunch Bob Alex

Physics
A 50 Kg box rests on a horizontal surface. The coefficient of Static friction between the box and surface is 0.30. The coeffient of Kinetic friction is 0.20. What is the frictional force on the box if a 140 N horizontal push is applied to it. If a 175 N horizontal push is ...

Math
The rectangular backboard of a basketball court needs to be assembled. Its area is given as 18,900 cm2 and the width as 1.8 m. What is the backboard’s length in metres? m

Chemistry
A gas occupies a volume of 4.64 x 102 mL at 519.57 mm Hg pressure. What will be its volume, at constant temperature, if the pressure is changed to 764.71 mm Hg?

Math
how to find out length of a rectangle area given 18900cm'2 width 1.8 what is length in metres

Math
Its area is given as 18,900 cm2 and the width as 1.8 m. What is the backboard’s length in metres? m

Math
Our parent function for log is log (x), so how does your function differ? 1) The leading negative sign. This reflects rhe function across the x-axis. 2) The (2 - x) inside the log function. Note that this is actually two transformations because 2 - x is equivalent to -x + 2. A...

Emergency Easy QUESTION
It depends on the colleges you're looking at and the high school you are attending. Colleges like to see rigor on your transcript so, if the college is very prestigious and your HS offered a lot of rigorous classes-- AP, gifted, honors, dual enrollment, etc.-- that might ...

English Grammar
Yes, that seems right to me. "I was referred... job," is a simple subject-verb-noun construction, "by... supervisor" is an adjective prep phrase describing "job opening," "John Smith" is the essential appositive, and the rest is ...

science
What are the answer choices?

L.A.
Yes I meant L.A. I have no idea why I put Math. But thank you so much you helped me a lot!

Math
When Scrooge tells Marley that Marley was always “a good man of business,” in Act 1, Scene 3 of A Christmas Carol: Scrooge and Marley, Marley responds, “BUSINESS!!! Mankind was my business. The common welfare was my business; charity, mercy, forbearance, ...

Math
In order, these equations are: 1) .25x + 40 2) .40x + 25 Where the charge per minute is the slope, the flat rate the y-intercept. We want to know for what number of minutes these two plans cost the same, so set equations (1) and (2) equal to each other and solve for x.

algebra
Yes. A polynomial can have, at most, a number of zeroes equal to it's degree. A third degree polynomial can therefore have three zeroes, however, Ray is arguing that the polynomial has four INTERCEPTS. While the terms "zeroes" and "intercepts" are often...

Linear Algebra
Let T : Rn-->Rn be a linear transformation, whose standard matrix is invertible. Show that if B = {v1, . . . , vn} is a basis for Rn, then {T(v1), . . . ,T(vn)} is also a basis for Rn.

English
Because that's an arrogant, Anglo-centric point of view?

Calculus
This is actually a related rates question, so you want rates of change: so the rate of change of volume, the rate of change of surface area. This is represented as the derivative, but before you go finding the first derivative, think on how you should use the change of radius ...

Calculus
X and Y move perpedicular to each other, forming a right triangle. As such, the distance between the cars is sqrt(X^2 + Y^2), where X = +50 km/hr, Y = +60 km/hr. (These are functions.) We want the RATE at which these cars are seperating, so take the first derivative of the ...

PreCal
This set is numbers strictly greater than 2. Because this relation is strict (> instead of >=), the left interval is a parens. There is no upper bound, so the right interval is infinity. (2, +INF)

PreCal
That the price "dropped steadily" implies a linear relationship, which would simply be change in price over change in time. (140 - 90) / 5 = -\$10 / week.

Math
Follow order of operations. In the first parens, 33 + 19 = 52. The second parens is 51. Our expression is now 52 * 2 * 51. Multiplication is associative, so it doesn't matter which order we do this in. My calculator gives me 5304.

Algebra
I'm getting D.

cs 2
Which part of this assignment are you having trouble with? The logic? Or File I/O?

statistics
The problem wants the test statistic for a one-proportion z-test, which we know because we're only given data for 1 test and that "492 / 806" implies a proportion. The sample statistic for this test is given by sqrt(pq / n). p = 492/806 (probability of success) q...

statistics
So the population distribution-- the distribution of ALL M&Ms-- is given in the problem: N(0.8565, 0.0518). However, we want to know what the mean weight will be if, instead of pulling from ALL M&Ms, we "randomly select 465 M&M plain candies." This is our sample. ...

statistics
You are given a normal distribution of a population. You want to know things about a sample distribution, so you should start with constructing a normal distribution for your sample of 465 M&Ms. The mean of this sample remains the same. The standard deviation is the population...

statistics
The normal distribution is N(25, 10). P(X > 20) = .691 So approximately 69.1% passed the exam. 69.1% of 100 students is 69 students.

geometry (check my answers)
All statements are true. A rectangle simply requires that a four-edged figure has 4 right angles and two sets of parallel lines. A square is a special case-- that all four sides are the same length, but it's still a rectangle. The rest of your answers are correct. :-) It ...

math
What's the question?

physics
Er, what's the question?

math
y = -x + 8. (7, 1) corresponds to (x, y), so just plug in the values into the equations and see which one works. For the above equation, 1 = -(7) + 8 1 = 1 This is true, so this is indeed the correct equation.

math
Yes, quadrant IV is correct. :-)

Sampling Distributions
A - The sample standard deviation is the population standard deviation over the square root of the sample size, 30 / sqrt(36). The mean of an approximately normal sample distribution is the same as the population mean, so the sample distribution is N(360, 5). B - If you want ...

stat
We construct a binomial distribution. The probability of "success" (a substandard rod) is .05. We have 300 trials. B(.05, 300) P(X < 20) = .881

Physics
First convert your angular speed from rpm to rad/s. You can then convert your angular speed to tangential speed with v = omega * r. (Be sure to convert that diameter into SI units!) Newton's second law gives us F = ma, where this is centripetal acceleration, so F = (mv^2)/...

math
Sure, sounds good to me. :-)

math
I don't understand the question?

Bio
Because unique identifiers mean that, given a name, someone could find out about the organism. If we had two things with the scientific name "cat," that would be a problem-- there are tons of cats. But since no two species of cats have the same two names, given a ...

Bio
Ah, but each scientific name is unique. Chip brand names may be ridiculous-- Lay's, Doritos, Cheetos, etc.-- but they're unique so they still serve as good identifiers. (Can you tell I'm sitting next to a vending machine?) (Fun fact, ursus is also Latin-- most ...

Bio
D. All scientific names identify an organism's genus and species. Usually this name is Latinate (interesting-ish story involving Linnaeus), though it doesn't have to be.

Geometry
That's not a math error, that's a conversion error. Answers are in yards, lengths are given in feet. Cheap trick-- I just noticed it myself.

Geometry
Are you told that this is a right triangle? If you aren't, you'll have to law of cosines for the length of the third side. You could then Heron's for the area.

Statistics
I would say A, though that's because I was taught an 8-part procedure for hypothesis testing, and B - D are their own separate steps. It does make sense that you'd define your hypotheses in the hypothesis step, though, and you really shouldn't be calculating the ...

Educational Technology
I agree with all three of your answers. :-)

Language arts
Without the passage, it's difficult to discern anything about questions 1-3. 4, however, should be D. The way the sentence is set up is to imply a contradiction, something like "Geese usually fly in a V formation but they aren't today." Unpredictable ...

Math
Here, let's define "success" to be that the plant doesn't grow. This would be 1 - .6 = .4. We construct a binomial distributions with 6 trials (6 seeds planted). We want 4 events. B(6, .4) P(X = 4) = .138

HELP PHYSICS PLS :)
This is a perfectly inelastic collision, so we know that energy is conserved. (Good job identifying the problem!) Assuming you choose your "0" PE point to be the bullet's initial height: E(i) = E(f) .5m(bullet)v(bullet)^2 = m(tot)gh(system), where h is the height...

Math PLZZZ HELP!!!
I'd go with the second and third choices. That the scatter plot has a positive trend tells you that you have a line of best fit with a positive slope. This satisfies both the second and third statements. The first answer assumes that all points on the graph fall exactly on...

Math
Multiply both sides of the inequality by 2. x <= -30, which is D.

Math
Are you sure that's all the data and that you typed that data in correctly? I haven't thrown this into my calculator, but just by observation, the range would be 27 - -52 = 79? None of those choices are correct if that's your complete data... (If you have to pick, ...

Physics
Let's start by converting everything to SI units. 15 m/hr/s = 6.71 m/s/s 65 m/hr = 29.1 m/s We have constant acceleration, so we can use our constant acceleration kinematic formulas. Here we initial velocity, final velocity, acceleration, and want time so we use v(f) = v(i...

Statistics
The probability of our event occurring is .8. We construct a binomial distribution, with 4 trials, of which we want 3 to occur. B(4, .8) P(3) = .4096

Math
Multiply both sides by 3729, yielding 3729tan(7)

Math
Actually, wait. You should be using tan, since you're given the adjacent side. (The lesson here: always draw a picture.) 120tan(36).

Math
The transit here is extraneous information-- it's simply a device used to measure angles (I assume). We know that the base of the right triangle is 120 feet. (Notice that the transit of 8ft is nonsensical in this problem doesn't make sense because we're solving for...

Math
Perimeter is the sum of all sides. For a rectangle, P = 120 = 2L + 2W. You are given that L = 3n W = n, so you can now do a substitution into the perimeter equation: 120 = 2(3n) + 2(n). Simplifying this, we get 120 = 8n, so n = 15. Revisiting our length and width equations, L...

Math
1/15.5 = 2/31

computer science
What specific part are you having trouble with? The packages? File I/O? What language?

calculus
Between y = 2x2 + 9x − 4 and y = −x2 + 6x + 2 for x in [−2, 2]

Language Arts
You are correct. :-) A conjunction joins two parts of a sentence together. A better example to describe this would be "Alice bought a calculator, and Ben bought a mouse." The conjunction "and" divides the sentence into two thoughts-- "Alice bought a ...

math
Set up a proportion: If Bill can type 10 pages in 24 minutes and we want to know how many pages he can do in 5.5 hours (330 minutes), a possible proportion is: 24/10 = 330/x Cross-multiplying we get 24x = 3300, so x = 3300/24 = 138 pages.

Algebra
The easiest way to justify this is to visualize the graph. We know from the first the signs of this equation that this quadratic opens upwards and know that it is shifted to be above the x-axis, so the quadratic never crosses the x-axis and therefore has no roots. You could ...

Math grade 7
Net daily change is revenue - expenditures, 12500 - 15000 = -2500. The overall change in the treasury's funds is 1.1Mil - 1Mil = 100K. To find out how many days, we divide the overall change by the net daily change in revenue: 100K / 2500 = 40 days.

Algebra 2
If it's multiple choice, plug and chug those points. Otherwise, you have two options: 1) Quadratic Regression 2) Conics I opt for quadratic regression given that I've not done conics in three years, lol f(x) = -x^2 + 5x -4

Reverse math confused
Her preliminary cost (prior to tax and tip) is regular price (p) - 2. Tax and tip is 20% of this preliminary cost, so total cost is 9 = 1.2(p - 2). p = \$9.50. (Nice coupon, there...)

Math
We know that after cutting 1/3 of the coil and 8m of the coil, 1/2 of the coil remains. This can be written as 1/3 + x = 1/2, where x will be 1/6. We know that this 1/6 of the coil is 8m, so the total length of the coil is 8 * 6 = 48m because one coil = 6 subcoils each of 8m.

physics
Where is Q located? I'll explain how to do this, since I don't know enough about this problem. Solve for the the bob's velocity right before it hits ball Q using energy equations: U(bob) = KE(bob) + U(Q). From here you can use your elastic equations to solve for ...

math
The volume of the tank is 3885 cubic centimeters. Volume is equivalent to length * width * height, in which you are provided both length and width. Your equation becomes 3885 = 18.5 * 15 * height Solving this, we get height = 14 cm.

Quadratic Equations
A quadratic equation's shape is a parabola. So anything with a curved trajectory would fit: throwing a ball / javelin / football / anything, shooting an arrow... Here's a fun picture: prntscr . com / arm214

test corrections for problems 6,11,12 and 23please
We want f(x) - g(x) and are given both equations. All you have to do is substitute: 9x^3=2x^2-5x+5 - (5x^3-7x+4) Be sure to distribute that negative sign! (I'd give you an answer but I'm not sure what that equals sign is supposed to be?)

test corrections for problems 6,11,12 and 23please
The sphere question is very similar to the cylinder question. Stick the provided value r into the provided surface area equation. SA = 4pi(2x+5)^2 Here you distribute / foil (2x+5) out when expanding, yielding 4pi(4x^2 + 20x + 25). Again, you should multiply each term by 4pi ...

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