HOMEWORK HELP Thread

[brat316]

dude nvm I figure it out

[Wootylicous]

You just draw it and figured it out ? awesomeness

[brat316]

I got another one ahhaha.



F(x)=F initial(x^2) Finitial= 10 N/cm^2

m=2kg

Xst is the rest position
mx''=mg-F(x)exact governing equation
my''+ky=0 systems dynamics form
y=(X-Xst)


Find K in N/m

then
set the as in motion and the amplitude drops by 1/2 in 4 seconds, this means motion is damped and that the governing equation is
my''+by'+ky=0
or y''+(2*gamma*Wn)y'+Wn^2y=0
find Gamma

[brat316]

Originally Posted by Wooty Magic!

You just draw it and figured it out ? awesomeness

well i was at it for a while and wnated to see where i was going wrong.

Now this one, i'm stuck on for sure. All I know is that it require taylor series to find K.

[brat316]

hows it coming along?

[brat316]

dude anything? I can sure use the help by like 12:00

[brat316]

I know i've been posting in here a lot . Alright last thing for a while, this one is pretty simple.


Here is the run down first, I'm trying to find a min mass flow rate for my project which needs to be 1 GPM, and max 4 GPM. Now water is going out of a 5 gallon jug, that has the top cut off, and the water is flowing into a PVC pipe. The area is already set at 1.5 inches, which I know is to big. I need to find the velocity of water at atm pressure, and then the diameter of the circle which the water will funnel through. I did some work I just need help making sure I did it right, basically a check over. think of it as a Deer Park 5 gallon bottle, like the ones for water dispenser, but the top cut off, and it flowing out the nozzle.



So, I know V=sqrt(2∗19.5inches∗387.6inches/s^2)
V=122.95 inches/sec, 10.245 ft/s = 614.7 ft/min

Now the simple equation of Q=VA

1 GPM->.13ft^3/min = 614.7ft/min * A(min
.03024 in^2 = A(min)
sqrt(.03024/∏)= r(min) = .09811 inches

We would have to reduce our inner diameter to .19622 inches.
Now is this right? I can't believe that? I was initial thinking it would be a DE since our mass flow would be varying, depending the height of the water, gravity would be pushing it through the main system.

[brat316]

[OSUGiants17]

Can someone find me a news article that shows an example of Derived Demand. Derived Demand is when the demand for the product directly affects the demand for the factors. For example, if no one needs taxi services in a small town, there is no need for the taxi service in that town since they won't make money.

[Razor]

Take your pick.

[OSUGiants17]

Originally Posted by Razor

Take your pick.

It's not in English, and they are all articles from the 70's and 80's

[Razor]

Originally Posted by OSUGiants17

It's not in English, and they are all articles from the 70's and 80's

That's not how it works. You go see who quoted the articles and find the ones relevant to your problem. Generally speaking there's no expiration date on scientific articles so you can pretty much pick whatever you like.

[Malaka]

So I am taking my first economics course in college... and well my first test came back an 80. I am a little disappointed by that, but anyway short-run and long run cost minimization is really giving me problems.

I have not taken calculus, so the derivative stuff is beyond me, but my professor focuses on that method so I am falling behind... the drop date was yesterday so now I am stuck. I fear the worst (which also includes me switching my major from business to something less math orientated)... worst part is I have no exercises or resources to practice with.

Would anyone like to spare some time to help me out? Any economics majors?

I would really appreciate it.

[jrdrylie]

I was an economics major although I didn't do too much with cost minimization in my studies. I also have some background in calculus so I might be able to help. Post the problem and I'll see if I know how to do it.

[WCH]

Originally Posted by Malaka

So I am taking my first economics course in college... and well my first test came back an 80. I am a little disappointed by that, but anyway short-run and long run cost minimization is really giving me problems.

I have not taken calculus, so the derivative stuff is beyond me, but my professor focuses on that method so I am falling behind... the drop date was yesterday so now I am stuck. I fear the worst (which also includes me switching my major from business to something less math orientated)... worst part is I have no exercises or resources to practice with.

Would anyone like to spare some time to help me out? Any economics majors?

I would really appreciate it.

Get this book: Quick Calculus: A Self Teaching Guide. You might be able to find it in the library. It was written for MIT freshmen majoring in physics who needed a crash course in Calculus because they hadn't taken it in HS. It can get you to speed on differential calculus within a few days (if you're solid with Algebra).

[Bosanac01]

Economics is simple stuff. I'm a business major myself, it's not fun but just ask question and stick with it, it always makes sense.

[Malaka]

Originally Posted by jrdrylie

I was an economics major although I didn't do too much with cost minimization in my studies. I also have some background in calculus so I might be able to help. Post the problem and I'll see if I know how to do it.

That's the thing... I have no problems... no exercises... I can't practice. Meanwhile I am here on a Friday night trading time that I could be enjoying myself trying instead to improve myself.

My textbook just has zero numerical examples or problems. I just have like two numerical equations he did on the board, and they are already solved. I understand the concept of

MPL/w = MPK/r
and
Q= F(L,K)

I guess I'll just make one up then...

(Long run example)
F(L,K)= sqrt of 3L x K
w= $9
r= 12$



Short Run Example k is constant

F(L,K)= sqrt of K x L
w= $5
r= $10
K= $40

[Malaka]

Originally Posted by Bosanac01

Economics is simple stuff. I'm a business major myself, it's not fun but just ask question and stick with it, it always makes sense.

I understand the graphs and concepts and the general idea... then when we get into the equations and formulas I just get lost. :/

[Malaka]

A wheat farmer has total production costs given by the equation TC=600+2Q, where Q is output, measured in bushels of wheat.

a. What is the farmer's marginal cost (MC) of production?
b. What is the farmer's fixed cost? Give some examples of what costs might be fixed for a wheat farmer.
c. Write the equation giving the farmer's variable cost as a function of quantity. What are examples of
variable costs for a farmer?
d. Write the equations for the farmer's average total cost (ATC) and average variable cost (AVC).

Here is an actual one I got for homework, if anyone is willing to give it a go.

[jrdrylie]

a. Marginal cost is $2 because marginal cost is the cost of producing one more unit. So each time Q increases by one, TC increases by $2.

b. Fixed cost is $600 because even if Q=0, the cost to the farmer is still $600. An example of a fixed cost is the mortgage he pays for his farm. Others might be salaries of non-hourly employees.

c. Variable cost I believe is just total costs minus fixed costs. So the formula is VC=TC-FC. For example, lets say the farmer produces 200 bushels (Q) of wheat. FC=$600. Q=200. So 600 + 2(200) = 1000 and thus variable costs are 400.

Variable costs include wheat seeds, labor costs, gasoline for the tractor, water bill used to water the land.

d. Average total cost is just total cost divided by Q. So it would be (600+2Q)/Q. In the example I used of Q = 200. That would be 1000/200, so ATC would be $5. AVC would just be $2 because this is a linear equation.

[Malaka]

Originally Posted by jrdrylie

a. Marginal cost is $2 because marginal cost is the cost of producing one more unit. So each time Q increases by one, TC increases by $2.

b. Fixed cost is $600 because even if Q=0, the cost to the farmer is still $600. An example of a fixed cost is the mortgage he pays for his farm. Others might be salaries of non-hourly employees.

c. Variable cost I believe is just total costs minus fixed costs. So the formula is VC=TC-FC. For example, lets say the farmer produces 200 bushels (Q) of wheat. FC=$600. Q=200. So 600 + 2(200) = 1000 and thus variable costs are 400.

Variable costs include wheat seeds, labor costs, gasoline for the tractor, water bill used to water the land.

d. Average total cost is just total cost divided by Q. So it would be (600+2Q)/Q. In the example I used of Q = 200. That would be 1000/200, so ATC would be $5. AVC would just be $2 because this is a linear equation.

The thing is he doesn't give me Q. VC = wages x labor + rent x capital. For C I don't know how to set up the equation for it.

Also are you sure I can just set Q to 0 to find MC and FC?

EDIT: For instance look at question 16

16. A local microbrewery has total costs of production given by the equation TC=500+10Q+5Q^2

This implies that the firm's marginal cost is given by the equation MC = 10 +10Q.
a. Write the equations showing the brewery's average total cost and average variable cost, each as a
function of Q.
b. Show the firm's MC, ATC and AVC on one graph.
c. What is the quantity produced at which the firm’s ATC is minimized?
d. What is the quantity produced at which the firm’s AVC is minimized?

It implies the MC = 10+10Q

*By the way these are just practice problems, you aren't just doing my homework for me I. I just legitimately need help.

[yo123]

Any Econ guys in here? I'm pretty sure this is easier than I'm making it...

[Malaka]

Would anyone like to take a crack at this stats problem? Part C is killing me but feel free to check over my answers for parts a and b :).

Wallen Accounting Services 9% of their tax returns selected for audit. Wallen has 6 new customers. Assume the chances of these 6 customers being audited are independent.

(a) What is the probability that all 6 new customers will be selected for audit?

(.09)^6= .0000005

(b) What is the probability that none of the 6 new customers will be selected for audit.

1-.09=.91

.91^6= (approx.) .569

(c) What is the probability that exactly one of the six new customers will be selected for audit?

Here is where I am stuck, I did come up with an answer but have no idea if it is correct.

First I did: 1-.569 to get .431

Then since there are 6 independent people who can be audited I divided .431 to get .07183.

I then subtracted .07183 fro, .431 to get .3591666667

I am really unsure if that is the right answer :/ I am sure its probably really simple, but please someone explain what I might be doing wrong. Thanks!

[bantx]

p = probability of audit = .09

n = probability of no audit = .91

(p + n)^6

6Combination5(pn^5)

6 * .09 * .91^5 = .336977 <--answer


Subtract 1 from P and that will always be your N

memorize your formula's malaka statistics is easy, if you know your formula's it's just plug and calculate.

[Bosanac01]

I have a finance problem that I'm probably over thinking.

Q: An investment will pay you $3,000 today, $8,000 in one year and $10,000 in two years. If the appropriate interest rate is 6%, what is this investment worth today?