With the information given we have:

Where W is the weight, k is the proportionality constant and r is the radius of the can's radus. Remember that the weight varies jointly so this key word means that you need to multiply the mentiones parameters by a proportionality constant k.
We simply need to reorganize the expression and isolate k for the frst answer:

Replacing by all the appropiate values we get:

For the second part knowing k we have:
Go to desmos type the equation and whatever number is on the x line is your answer
No because if you do the math if you do 215 x 48 in doesn't reach to 12000 at all.