The number w is 110% greater than the number z. The number z is 55% less than 50. What is...
GMAT Problem-Solving and Data Analysis : (PS_DA) Questions
The number \(\mathrm{w}\) is \(110\%\) greater than the number \(\mathrm{z}\). The number \(\mathrm{z}\) is \(55\%\) less than \(50\). What is the value of \(\mathrm{w}\)?
1. TRANSLATE the second condition first
- Given: "z is 55% less than 50"
- This means: \(\mathrm{z = 50 - (55\% \text{ of } 50)}\)
- Calculate: \(\mathrm{z = 50 - 0.55(50)}\)
\(\mathrm{z = 50 - 27.5}\)
\(\mathrm{z = 22.5}\)
2. TRANSLATE the first condition
- Given: "w is 110% greater than z"
- This means: \(\mathrm{w = z + (110\% \text{ of } z)}\)
\(\mathrm{w = z + 1.10z}\)
\(\mathrm{w = 2.10z}\) - Key insight: "110% greater than" means the original amount PLUS 110% more
3. SIMPLIFY by substitution
- Substitute \(\mathrm{z = 22.5}\) into \(\mathrm{w = 2.10z}\)
- \(\mathrm{w = 2.10(22.5)}\)
\(\mathrm{w = 47.25}\)
Answer: \(\mathrm{47.25}\) (also acceptable as \(\mathrm{189/4}\))
Why Students Usually Falter on This Problem
Most Common Error Path:
Weak TRANSLATE skill: Students misinterpret "110% greater than z" as meaning "110% of z"
They think \(\mathrm{w = 1.10z}\) instead of \(\mathrm{w = 2.10z}\). This fundamental misunderstanding of percentage language leads them to calculate \(\mathrm{w = 1.10(22.5) = 24.75}\), which doesn't match any typical answer choice and causes confusion and guessing.
Second Most Common Error:
Weak TRANSLATE skill: Students misinterpret "55% less than 50" as "55% of 50"
They calculate \(\mathrm{z = 0.55(50) = 27.5}\) instead of \(\mathrm{z = 50 - 27.5 = 22.5}\). Even if they correctly handle the "110% greater than" part, they end up with \(\mathrm{w = 2.10(27.5) = 57.75}\), leading to an incorrect final answer.
The Bottom Line:
The key challenge is correctly translating percentage language - "X% greater than" means 100% + X% of the original, while "X% less than" means 100% - X% of the original. Students who rush through the translation step often confuse these constructions with simpler "X% of" calculations.