A contest prize of $200 is divided between two winners. The first winner receives $x and the second winner receives...
GMAT Algebra : (Alg) Questions
A contest prize of \(\$200\) is divided between two winners. The first winner receives \(\$x\) and the second winner receives \(\$y\). The first winner receives \(\$20\) more than \(3\) times what the second winner receives. What is the value of x?
45
140
150
155
1. TRANSLATE the problem information
- Given information:
- Total prize = \(\$200\) (split between two winners)
- First winner receives \(\$x\), second winner receives \(\$y\)
- First winner receives \(\$20\) more than 3 times what second winner receives
- What this tells us mathematically:
- \(\mathrm{x + y = 200}\)
- \(\mathrm{x = 3y + 20}\)
2. INFER the solution approach
- We have two equations with two unknowns - this is a system of equations
- Since the second equation already isolates x, substitution method will work efficiently
- Strategy: substitute the expression for x into the first equation
3. SIMPLIFY using substitution
- Substitute \(\mathrm{x = 3y + 20}\) into \(\mathrm{x + y = 200}\):
- \(\mathrm{(3y + 20) + y = 200}\)
- \(\mathrm{4y + 20 = 200}\)
- \(\mathrm{4y = 180}\)
- \(\mathrm{y = 45}\)
4. SIMPLIFY to find x
- Now that \(\mathrm{y = 45}\), substitute back:
- \(\mathrm{x = 3(45) + 20}\)
- \(\mathrm{x = 135 + 20}\)
- \(\mathrm{x = 155}\)
Answer: D. 155
Why Students Usually Falter on This Problem
Most Common Error Path:
Weak TRANSLATE skill: Students struggle to convert "20 more than 3 times what the second winner receives" into the equation \(\mathrm{x = 3y + 20}\). They might write incorrect relationships like:
- \(\mathrm{x = 3y - 20}\) (subtracting instead of adding)
- \(\mathrm{x = 3(y + 20)}\) (misplacing the parentheses)
- \(\mathrm{3x + 20 = y}\) (completely backwards relationship)
Any of these translation errors leads to a different system of equations and an incorrect final answer that doesn't match any given choice, causing confusion and guessing.
Second Most Common Error:
Poor SIMPLIFY execution: Students correctly set up the equations but make algebraic errors when solving \(\mathrm{4y + 20 = 200}\). Common mistakes include:
- Forgetting to subtract 20 from both sides: \(\mathrm{4y = 200}\), so \(\mathrm{y = 50}\)
- Arithmetic errors: \(\mathrm{200 - 20 = 160}\) (instead of 180), leading to \(\mathrm{y = 40}\)
These errors cascade to wrong values of x, potentially leading them to select Choice B (140) or other incorrect options.
The Bottom Line:
This problem tests whether students can accurately translate complex verbal relationships into mathematical equations. The phrase "20 more than 3 times" requires careful parsing - students must recognize the order of operations in language and convert it precisely to algebra.
45
140
150
155