Step-by-step explanation:

To find the volume of a cylinder, we use the formula:

V = πr²h

Where:

V = Volume

π = 3.14 (approximate value of Pi)

r = radius

h = height

Cylinder 1:

Given,

r = 3 mm and h = 12 mm

Using the formula,

V = πr²h

V = 3.14 x 3² x 12

V = 339.12 mm³

Therefore, the volume of Cylinder 1 is 339.12 mm³.

Cylinder 2:

Given,

r = 12 cm and h = 10 cm

Converting radius to cm, we get:

r = 12 cm

Using the formula,

V = πr²h

V = 3.14 x 12² x 10

V = 4,523.2 cm³

Therefore, the volume of Cylinder 2 is 4,523.2 cm³.

Cylinder 3:

Given,

r = 5 dm and h = 9 dm

Converting radius and height to cm, we get:

r = 5 dm = 50 cm

h = 9 dm = 90 cm

Using the formula,

V = πr²h

V = 3.14 x 50² x 90

V = 353,430 cm³

Therefore, the volume of Cylinder 3 is 353,430 cm³.