Elasticity of Demand questions

I'm not sure if I've done this problem correctly.

The problem is:

1. x= -5/4p+20; p=10

How I Solved It:

(-5/4(10))/(-5/4(10)+20)

= -5/3

Is this right or if I've done something wrong, where did I go wrong specifically?

The Other Problem:

2. x= 1/5(225-p^2); p=10

How I Solved It:

x= 45-0.2p^2

(-0.2(10)^2)/(45-0.2(10)^2)

= -20/25

= -0.8

Again, is this right or if wrong, *where* did I go wrong?

Thanks.

Re: Elasticity of Demand questions

Hey AntoninaFinn.

Are you just trying to evaluate what x is given p for both questions?

Re: Elasticity of Demand questions

Quote:

Originally Posted by

**AntoninaFinn** I'm not sure if I've done this problem correctly.

The problem is:

1. x= -5/4p+20; p=10

This is ambiguous. Do you mean x= -(5/4)p+ 20 or x= -5/(4p)+ 20?

Quote:

How I Solved It:

(-5/4(10))/(-5/4(10)+20)

= -5/3

Is this right or if I've done something wrong, where did I go wrong specifically?

Yes, that is correct.

Quote:

The Other Problem:

2. x= 1/5(225-p^2); p=10

How I Solved It:

x= 45-0.2p^2

(-0.2(10)^2)/(45-0.2(10)^2)

= -20/25

= -0.8

Again, is this right or if wrong, *where* did I go wrong?

That is NOT what I get. What did you get for the derivative of x with respect to p?

Thanks.[/QUOTE]