Answer:
Step-by-step explanation:
Hi Millie.
First we can realize that the number of cubes of each type does not matter, only the ratios between them. We see that if there are x yellow cubes, there are 3x blue cubes. And therefore, there are 5*3x green cubes, or 15x green cubes. This means that the cubes are in a 1:3:15 ratio, or that for every 1 yellow cube, there are 3 blue and 15 green cubes.
Now we can find the probability of picking a yellow cube. Since there are 18 non-yellow cubes for every yellow cube, this means that there is a 1/19 possibility of picking a yellow cube.
Consider the closed region

bounded simultaneously by the paraboloid and plane, jointly denoted

. By the divergence theorem,

And since we have

the volume integral will be much easier to compute. Converting to cylindrical coordinates, we have




Then the integral over the paraboloid would be the difference of the integral over the total surface and the integral over the disk. Denoting the disk by

, we have

Parameterize

by


which would give a unit normal vector of

. However, the divergence theorem requires that the closed surface

be oriented with outward-pointing normal vectors, which means we should instead use

.
Now,



So, the flux over the paraboloid alone is
It is A because if you subtract 9 and 6 you get 3 and then you add the 4 and get 7