Praxis Core Academic Skills for Educators: Mathematics (5733)GeometryMedium
A company is designing a new cylindrical water tank. The tank has a diameter of 8 feet and a height of 15 feet. What is the volume of the tank?
- A960π cubic feet
- B240π cubic feet
- C120π cubic feet
- D60π cubic feet
Show answer & explanationAnswer & explanation
Correct answer: B. 240π cubic feet
The volume of a cylinder is given by the formula V = πr²h, where r is the radius and h is the height. Remember that the radius is half of the diameter. So, r = 8/2 = 4 feet.
Why the other options are wrong
- A. This is incorrect; it might result from using the diameter as the radius in the formula.
- C. This is incorrect; it might result from using 2r instead of r² in the formula.
- D. This is incorrect; it might result from using the diameter instead of radius for r or an incorrect calculation.
Volume of a Cylinder
The amount of three-dimensional space occupied by a cylinder, calculated by the area of its base times its height.
- Formula: V = πr²h.
- The base is a circle, so its area is πr².
- Diameter (d) is twice the radius (r), so r = d/2.
Memory trick: Cylinder volume: 'Pi' 'R' 'Squared' times 'Height'!