BTGmoderatorLU wrote: ↑Wed Jul 07, 2021 4:39 pm
Source: Official Guide
What is the volume of the right circular cylinder X?
1) The height of X is 20.
2) The base of X has area \(25\pi.\)
The OA is
C
Target question: What is the volume of the right circular cylinder X ?
---------------------------------------------------------------------------------
Aside: A
right circular cylinder is a cylinder whose bases are aligned directly above the other.
So, the cylinder on the left (below) is a right cylinder, and the one on the right is an oblique cylinder
---------------------------------------------------------------------------------
Key property: Area of cylinder = pi r^2 h
Statement 1: The height of X is 20
Since we still don't know the radius of the cylinder, statement 1 is NOT SUFFICIENT
Statement 2: The base of X has area 25π.
Area of a circle = pi r^2
So statement 2 is telling us that: pi r^2 = 25 pi
Since we still don't know the height of the cylinder, statement 2 is NOT SUFFICIENT
Statements 1 and 2 combined
Statement 1 tells us that h = 20
Statement 2 tells us that pi r^2 = 25 pi
So
the volume of the cylinder = pi r^2 h = (25 pi)(20) = 500 pi
Since we can answer the
target question with certainty, the combined statements are SUFFICIENT
Answer: C
Cheers,
Brent
