GED Mathematical Reasoning TestQuantitative Problem Solving with MeasurementMedium
A client wants to install new baseboards around a circular room. If the room has a radius of 4 meters, what is the approximate length of baseboard needed? (Use π ≈ 3.14)
- A25.12 meters
- B100.48 meters
- C50.24 meters
- D12.56 meters
Show answer & explanationAnswer & explanation
Correct answer: A. 25.12 meters
The length of baseboard needed corresponds to the circumference of the circular room. The formula for circumference is C = 2πr. With a radius of 4 meters and π ≈ 3.14, the circumference is 2 × 3.14 × 4 = 25.12 meters.
Why the other options are wrong
- B. This is 4πr², which is incorrect and much too large.
- C. This is πd² or 2πr², which is incorrect for circumference.
- D. This is πr, which is half the circumference.
Circumference of a Circle
The circumference of a circle is the distance around its edge. It is analogous to the perimeter of a polygon.
- Formula: C = 2πr (where r is the radius)
- Alternative Formula: C = πd (where d is the diameter)
- Units are linear units (e.g., meters, feet)
Memory trick: Circumference is two pi R, sailing around the circle's star!