We know the diameter, so we can easily find the radius. The diameter is twice as long as the radius, so we divide the diameter by 2 to find the radius. This is equal to 6/2 = 3. Now, we plug our numbers into the formula.
This could also be written:
Both 27 pi cubic meters and 84.82 cubic meters are correct answers, so choose whichever one you think your teacher would prefer.
The formula of the volume of a cylinder is: V = PI (3.14) times radius squared times height, so... V = PI times half of the diameter, which is 3, squared and times by 3 (the meters of height). Now, V = PI times 9 times 3. PI (3.14) times 9 = 28.26 times 3 = 84.78. So, the volume of the cylindrical tank is 84.78 meters cubed (volume is always cubed).