Answer:
15 centimeters.
Step-by-step explanation:
We must calculate the volume of each cylinder and add it, like this:
v = pi * (r ^ 2) * l
replacing:
v1 = 3.14 * (5 ^ 2) * 7
v1 = 549.5
v2 = 3.14 * (10 ^ 2) * 5
v2 = 1570
The sum would be:
549.5 + 1570 = 2119.5
That would be the volume of the cylindrical disk, this case would be the same formula only that it would not be length but thickness, like this:
v = pi * (r ^ 2) * t
we want to know r, therefore:
r ^ 2 = v / pi * t
replacing:
r ^ 2 = 2119.5 / (3.14 * 3)
r ^ 2 = 225
r = 15
which means that the radius would be 15 centimeters.
