00:01
In this problem, we're using the given production function for the production of bar stools to figure out how much machines, which is represented by k, and how many units of labor represented by l, we want to use for this project.
00:16
So we're given the given production function.
00:18
We're told that the budget is $10 ,000, and that it costs $50 per unit k or l.
00:24
And in the end, we want the quantity q to equal 10 for our production.
00:30
So the first part, we are saying that the owner reasons that since both labor and machines cost the same, he will use the same amount of each of these two inputs to get to his desired output of 10.
00:44
So in order to figure out how much of each will hire, we're going to set up a system of equations.
00:50
So if he wants k to equal l, we're going to just say that we'll just set these two equal to a new variable x.
01:00
So both of these are equal to x in this problem, since he wants to use the same amount of both.
01:05
And then we're also going to say that q is equal to 10, right? so 10 is equal to 0 .1.
01:12
And then since k and l are both equal to x, it's going to be 0 .1.
01:15
Let me put these in front, 0 .1 times x, is going to be raised with this little carrot to the point two, and then also multiplied by x again, which is equal to l, which is going to be raised to the 0 .8 power.
01:34
All right, so now we have our quantity 10, right, is equal to 0 .1 times x to 0 .2, times x to the 0 .8.
01:42
And then if we simplify this and we combine the two x's raised to the point two and point eight power, we're going to get that 10 is equal to 0 .1 times x to the first, right? because when you simplify this, you're going to add up the 0 .2 plus 0 .8 to simplify these powers.
02:02
So we're going to get 10 is 0 .1 times x.
02:04
If we divide 10 by 0 .1, we're going to get 100 is equal to x.
02:08
All right.
02:09
So now we know that we're going to want 100.
02:12
Units of both labor and machines.
02:14
Okay, is 1 equals l is 100.
02:19
So then if we know that each unit costs $50, we're going to say $50 multiplied by 100, it's going to be $5 ,000 worth of both k and l.
02:37
So we're going to buy $5 ,000 worth of machines and also $5 ,000 worth of machines, of labor to get this project done.
02:45
So total cost to produce 10 barstools is going to be equal to his exact budget limit, $10 ,000.
02:56
All right.
02:57
So now let's say that he takes a different approach, and he wants to produce at the point where the marginal productivity of both capital and labor are equal, not the average productivity, right? so how do we figure out what marginal productivity is.
03:13
We're simply just going to take the derivative of this production function with respect to first capital, k, and then labor l.
03:21
So i'm going to call this the marginal productivity of capital for mpk.
03:27
So mpk is going to be equal to.
03:30
So taking the derivative, you're going to do 0 .1 times 0 .2, so it's going to be 0 .02, and then multiplied by k to the 0 .2 minus 1, so k to the negative 0 .08 power multiplied by l to the point 8, right? because if we're taking the derivative with respect to k, l to the point is treated like a constant, right? so l to the point 8.
04:05
Oh, sorry, it's k to the negative point 8.
04:08
Right, so our marginal product of capital is 0 .02 times k to the negative 0 .8 times l to the point 8.
04:16
All right.
04:16
And then if we do marginal product of labor, so mpl, we're going to find that that is equal to, so 0 .08, because 0 .1 times the power that l is raised to originally, right? so 0 .08 times, and we keep k constant, times k to the 0 .2, and then finally times l to the, negative 0 .2.
04:44
All right, so that is our marginal product of labor.
04:49
Okay, so now what we're going to want to do, if we want to produce at the point where these two are equal, we're simply going to set mpk equal to mpl.
04:56
Right, so at 0 .02 is going to be equal to.
05:00
How about we actually just copy and paste this? so this up here, this mpk, is going to be equal to this mpl up here, like that.
05:15
All right.
05:16
And then if we simplify this, so if we bring the k to the raise to the point two power, which is on the right side of the equation, divide both sides and bring it over to the left, or sorry, if we bring the k to the negative point eight over to the right, we're going to get something out like this.
05:34
So let's do, so we're going to have, actually let me just write this out over here.
05:40
It'll be easier to visualize.
05:41
So we have l to the point.
05:43
8 on the left side, and then we divide both sides by the l to the negative 0 .2.
05:50
So negative 0 .2.
05:52
And then we're going to bring the k over to the right side, so it equals k to the 0 .2, divided by k to the negative 0 .8 .8.
06:02
Right? and then we still have the 0 .02 on the left and the 0 .08 on the right.
06:08
So if we divide 0 .08 by 0 .02, we're going to get a constant of 4 on this right side.
06:12
All right, so then what we're seeing here is when we simplify these fractions, we can bring up, so l to the negative point two, if it's in the denominator, you simply take away the negative sign and put it in the numerator, and then l to the point 8 and l to the point two are going to simply give us l to the first power, which is just l.
06:32
And the same thing is going to happen on the other side if we bring that up.
06:36
So it's going to be l to the first equals 4k to the first, so l equals 4k .k.
06:42
So that is our first equation that we're dealing with here.
06:46
So l is going to be equal to 4k...