00:01
Okay, so we're given this equation which tells us the amount of time in hours to reduce the xth unit.
00:07
And what we want to do is we want to use this equation to find how long it takes a worker to produce units 1 through 20 and then 20 through 40.
00:16
So for 1 through 20, the way that we're going to do this is we're just going to find the integral of our equation from 1 to 20.
00:22
And again, because this tells us the amount of time for the x unit, if we take the integral of that, then we'll find the amount of time for the total.
00:31
Or the total amount of time to produce those units.
00:35
So that's why you're taking the integral.
00:37
So we have the integral of 2 plus 0 .3 times 1 over x, dx.
00:44
And this is equal to just you doing anti -differentiation.
00:49
The anti -derivative of 2 is 2x, and then you're plusing 0 .3 times the natural log of x, and this is from 1 to 20.
01:00
And the reason that the natural log of x is the anti -derivative of 1 over x is because the derivative of the natural log of x is just 1 over x.
01:09
Okay, so now let's plug in our points 1 and 20.
01:13
So for 1, we would have 2 plus 0 .3 times the natural log of 1, and the natural log of 1 is just 0.
01:20
So this would just be 2.
01:22
We're minusing.
01:23
And if we plug in 20, we have 20 times 2, which is actually 40, and then we're adding 0 .3.
01:30
Three times the natural log of 20.
01:34
And so if we put this into a calculator, the natural log of 20 is about 2 .99, and if we times that by 0 .3, and if we add that to 40, and we minus 2, should get an answer that is equal to about 38 .9 hours.
02:00
So the total amount of time that it would take to produce units 1 through 20 would be 38 .9 hours...