A wind vane rotates clockwise through an angle equal to (\frac{7}{15}) of a full revolution.One full revolution measures 360 degrees.What...
GMAT Geometry & Trigonometry : (Geo_Trig) Questions
- A wind vane rotates clockwise through an angle equal to (\frac{7}{15}) of a full revolution.
- One full revolution measures \(360\) degrees.
- What is the measure of this rotation, in degrees? Enter your answer as an integer.
1. TRANSLATE the problem information
- Given information:
- Wind vane rotates \(\frac{7}{15}\) of a full revolution clockwise
- One full revolution = \(360\) degrees
- Need the rotation measure in degrees
- What this tells us: We need to find \(\frac{7}{15}\) of \(360\) degrees
2. SIMPLIFY the calculation
- Set up: \(\frac{7}{15} \times 360°\)
- Recognize that \(360 \div 15 = 24\)
- So: \(\frac{7}{15} \times 360 = 7 \times 24 = 168°\)
Answer: 168
Why Students Usually Falter on This Problem
Most Common Error Path:
Weak TRANSLATE skill: Students may not recognize that "\(\frac{7}{15}\) of a full revolution" means they need to multiply \(\frac{7}{15} \times 360\).
Some students might think they need to divide \(360\) by \(\frac{7}{15}\), or they might get confused about whether to multiply or divide. Others might not connect "\(\frac{7}{15}\) of" with multiplication at all.
This leads to confusion and incorrect calculations, potentially resulting in answers like \(77\) \((360 \div 7 \times 15)\) or other incorrect values.
Second Most Common Error:
Poor SIMPLIFY execution: Students correctly set up \(\frac{7}{15} \times 360\) but make calculation errors.
They might calculate this as \((7 \times 360) \div 15 = 2520 \div 15\) and then make division errors, or they might not recognize that \(360 \div 15 = 24\) simplifies the problem significantly.
This leads to arithmetic mistakes that produce incorrect integer answers.
The Bottom Line:
This problem tests whether students understand that "fraction of" means multiplication and can perform the arithmetic efficiently. The key insight is recognizing that fractions of standard measurements (like \(360°\)) often simplify nicely.