00:01
In this problem, we're given that c varies jointly with d.
00:05
So that means c is equal to some constant times d.
00:10
And also, it varies jointly with the square of g.
00:14
And so that means we also have g in the numerator, and it's the square of g.
00:19
So we have g squared.
00:21
Now, we don't know what this constant is yet, but we can use the point we're given to figure out what it is.
00:27
So if c is 30, we can plug that in.
00:30
And we have our constant times d, which is 15, and g, which is 2.
00:39
And so now we can figure out what k is by dividing by 15 and 2 squared.
00:45
So 30 divided by 15 is equal to 2, and then we divide by 2 squared...