Urgent Help Please :( Maths Problems

[Jackass]

Hi, really struggling with some revision questions that I have to have done tonight and struggling quite significantly. Could anyone help please? On a side note, if I'm sturggling with this kind of maths, is an Economics degree a bad idea??

Would really really appreciate help.

Thank you so much for help lads, so lost, so bummed right now, and need this done tonight.

Question 1

1.Given the consumption function C = 20 + 3Y0.4 , the equation for the marginal propensity to Consume (MPC) can be written as

Answer
A. – (19 + 3Y0.4)
B. None of these
C. 1 – 1.2Y – 0.6
D. 1.2Y –0.6 – 1
E. 1.2 Y – 0.6

Question 2

1. If the Average Cost function is AC = 4Q + 9 + 3/Q then the Marginal Cost can be written as:
Answer
A. 4Q3 + 9Q2 + 3Q
B. 8Q + 9
C. 12Q2 + 18Q + 3
D. 4Q2 + 9Q +3
E. None of these

Question 3

1.Differentiating the function y = (3x3+2x2 + x + 5)2 with respect to x gives the first derivative:
Answer
A. 2(3x3+2x2 + x + 5)
B. None of these
C. 2(3x3+2x2 + x + 5)2
D. 2(3x3+2x2 + x + 5) (9x2+4x + 1)
E. (9x2+4x + 1)

Question 4

1. Given the demand function: Q = 100 – 2P, the elasticity of demand when P = 10 is given as
Answer
A. – 1/2
B. –2
C. – 0.8
D. – 1/5
E. None of these

Question 5

1.The first derivative, dy/dx of the function y = ln (2x+1 ) is
Answer
A. 1 / (2x + 1)
B. 2 / (2x + 1)
C. 2x + 1
D. (2x + 1) / 2
E. None of these

Thanks for help.

fergalr

[Jackass] wrote: »

Hi, really struggling with some revision questions that I have to have done tonight and struggling quite significantly. Could anyone help please? On a side note, if I'm sturggling with this kind of maths, is an Economics degree a bad idea??

Would really really appreciate help.

Thank you so much for help lads, so lost, so bummed right now, and need this done tonight.

Question 1

1.Given the consumption function C = 20 + 3Y0.4 , the equation for the marginal propensity to Consume (MPC) can be written as

Answer
A. – (19 + 3Y0.4)
B. None of these
C. 1 – 1.2Y – 0.6
D. 1.2Y –0.6 – 1
E. 1.2 Y – 0.6

Question 2

1. If the Average Cost function is AC = 4Q + 9 + 3/Q then the Marginal Cost can be written as:
Answer
A. 4Q3 + 9Q2 + 3Q
B. 8Q + 9
C. 12Q2 + 18Q + 3
D. 4Q2 + 9Q +3
E. None of these

Question 3

1.Differentiating the function y = (3x3+2x2 + x + 5)2 with respect to x gives the first derivative:
Answer
A. 2(3x3+2x2 + x + 5)
B. None of these
C. 2(3x3+2x2 + x + 5)2
D. 2(3x3+2x2 + x + 5) (9x2+4x + 1)
E. (9x2+4x + 1)

Question 4

1. Given the demand function: Q = 100 – 2P, the elasticity of demand when P = 10 is given as
Answer
A. – 1/2
B. –2
C. – 0.8
D. – 1/5
E. None of these

Question 5

1.The first derivative, dy/dx of the function y = ln (2x+1 ) is
Answer
A. 1 / (2x + 1)
B. 2 / (2x + 1)
C. 2x + 1
D. (2x + 1) / 2
E. None of these

Thanks for help.

I'm not an economist, and I haven't done these before.

But these questions are all about basic differential calculus.

In most of the cases, what you are asked to find, is the differential of what you are given.

You can google for what the economic terms mean - the wikipedia pages tell you what you have to differentiate to get what the question asks.

Eg:
http://en.wikipedia.org/wiki/Price_elasticity_of_demand

http://en.wikipedia.org/wiki/Marginal_propensity_to_consume
says that marginal propensity to consume is the derivative of consumption, C, with respect to income, Y.

I.e. its dC/dY - so you would differentiate to get the answer.



As to how you differentiate a specific formula - well, you apply the rules of basic differentiation - you should find a book, or online resource, explaining basic differential calculus, and have a read of it. The kahn academy has videos - and there's lots of differential calculus tutorials out there.

There's not really a whole load more help I can give on that subject.


On the specific questions - I don't understand question 1) - I'm not completely clear on what the notation means (is that 'to the power of 0.4'?) and I can't see an answer that matches up - maybe I'm missing something?


Q4 is slightly trickier than the others (it requires a little more than differentiation). Here is a simple tutorial, that comes up when you google for it: http://economics.about.com/cs/micfrohelp/a/calculus_d.htm

[Jackass] wrote: »

On a side note, if I'm sturggling with this kind of maths, is an Economics degree a bad idea??

While it can seem intimidating at the outset, I'd honestly say basic differential calculus is one of those things that everyone can learn - with some time to study it.
It might require some study though, to understand whats going on - its not really a last minute, late on sunday night, kind of subject.

Lots of people get through economics degrees, and do little maths. So it's probably possible to get through the degree, avoiding maths - depending on where you are studying.
I'd say this is probably a very bad thing though, and that if you want to be good at economics, you should go through the maths.

But I'm not an economist. I guess it depends what you want to do afterwards.
If you put in the time, I reckon you should be able to get a handle on these more basic points, though.

Hope that's some help - can't see a way to help more, without either doing the questions for you, or starting to explain differentiation, which is better left to other resources.