00:01
Hi there.
00:01
In this problem, we're asked to repeat the previous problem about the iq and the sixth graders just with slightly different x and y parameters.
00:11
So i'll kind of assume you've done that one already.
00:14
If not, you can watch the video on that one, but we'll jump into it a little faster so we don't have to start from scratch again.
00:23
The only difference, like i said, are these x and y values.
00:27
So when we sketch our region r, that we're going to start from scratch again.
00:31
That we're going to start from scratch again.
00:31
The only difference, like i said, are these x and y values.
00:31
So when we sketch our region r, we're we're integrating over, well, x goes from 6 to 14, so the base now is 8, and y goes from 8 to 10, so the base is 2, and we see that yet again we have an area of 16, so the area of our region r is 16, and i think they did that on purpose, so we'll see, even though the area is the same, we can expect to get a very different average value because it's a different part of the x, y plane.
01:06
Okay, so the average value of q over the region r, just by definition, is one over the area of r times a double integral over r of the function q.
01:27
The area of r we said is again 16.
01:32
The function q is still 100 times x over y.
01:36
We'll integrate again x first, then y and the x goes from 6 to 14 y goes from 8 to 10 so here's our integral and we just need to evaluate this so it'll feel just like the previous example let's take the 100 out right away from here and go ahead and take antiderivative of x over y with respect to x while the y is a constant so with respect to x that's just x squared over 2 from 6 to 14 so go ahead and evaluating in the middle.
02:32
So we have to plug in 14, 6, and then subtract the difference.
02:36
14 squared is 196 over 2 then.
02:41
6 squared is 36, also over 2...