At a craft fair, Ruth's total revenue from selling 2 types of floral arrangements was $832. She sold x arrangements...
GMAT Data Sufficiency : (DS) Questions
At a craft fair, Ruth's total revenue from selling 2 types of floral arrangements was $832. She sold \(\mathrm{x}\) arrangements of Type A for \(\mathrm{y}\) dollars each and \((131 - \mathrm{x})\) arrangements of Type B for \((\mathrm{y} + 3)\) dollars each. If \(\mathrm{x}\) and \(\mathrm{y}\) are both integers, did Ruth sell more Type A arrangements than Type B arrangements?
- If Ruth had sold 2 more Type A arrangements and 5 more Type B arrangements, her total revenue would have been $882.
- If Ruth had sold \((131 - \mathrm{x})\) Type A arrangements and \(\mathrm{x}\) Type B arrangements, her total revenue would have been more than $832.
Understanding the Question
The question asks us: Did Ruth sell more Type A arrangements than Type B arrangements?
Let's break this down:
- Ruth sold x Type A arrangements and (131 - x) Type B arrangements
- We need to determine if \(\mathrm{x} > (131 - \mathrm{x})\)
- This simplifies to: \(\mathrm{x} > 65.5\)
- Since x must be an integer, we're asking: Is \(\mathrm{x} ≥ 66\)?
This is a yes/no question - we need a definitive "yes" or "no" answer.
Given information:
- Total revenue = $832
- Type A price = y dollars each
- Type B price = (y + 3) dollars each (Type B costs $3 more)
- Both x and y are integers
- Revenue equation: \(\mathrm{xy} + (131 - \mathrm{x})(\mathrm{y} + 3) = 832\)
Expanding this equation:
\(\mathrm{xy} + 131\mathrm{y} + 393 - \mathrm{xy} - 3\mathrm{x} = 832\)
\(131\mathrm{y} - 3\mathrm{x} = 439\)
What makes a statement sufficient? We need to determine whether x is definitely ≥ 66 or definitely < 66. We don't need the exact value of x - just which side of 65.5 it falls on.
Analyzing Statement 1
Statement 1 tells us: If Ruth had sold 2 more Type A arrangements and 5 more Type B arrangements, her total revenue would have been $882.
This gives us a new scenario:
- Type A: (x + 2) arrangements at y dollars each
- Type B: (131 - x + 5) = (136 - x) arrangements at (y + 3) dollars each
- New revenue = $882
Setting up the equation for this new scenario:
\((\mathrm{x} + 2)\mathrm{y} + (136 - \mathrm{x})(\mathrm{y} + 3) = 882\)
Expanding step by step:
\(\mathrm{xy} + 2\mathrm{y} + 136\mathrm{y} + 408 - \mathrm{xy} - 3\mathrm{x} = 882\)
\(138\mathrm{y} - 3\mathrm{x} = 474\)
Now we have two equations:
1. Original scenario: \(131\mathrm{y} - 3\mathrm{x} = 439\)
2. New scenario: \(138\mathrm{y} - 3\mathrm{x} = 474\)
Subtracting equation 1 from equation 2:
\((138\mathrm{y} - 3\mathrm{x}) - (131\mathrm{y} - 3\mathrm{x}) = 474 - 439\)
\(7\mathrm{y} = 35\)
\(\mathrm{y} = 5\)
Substituting y = 5 back into the original equation:
\(131(5) - 3\mathrm{x} = 439\)
\(655 - 3\mathrm{x} = 439\)
\(3\mathrm{x} = 216\)
\(\mathrm{x} = 72\)
Since x = 72, which is greater than 65.5, Ruth sold more Type A arrangements than Type B arrangements.
[STOP - Statement 1 is Sufficient!]
This eliminates choices B, C, and E. The answer must be A or D.
Analyzing Statement 2
Now let's forget Statement 1 completely and analyze Statement 2 independently.
Statement 2 tells us: If Ruth had sold (131 - x) Type A arrangements and x Type B arrangements, her total revenue would have been more than $832.
Here's the elegant insight: Statement 2 is saying that if we swap the quantities between Type A and Type B, the revenue increases.
Let's think about what happens when we swap:
- Original setup: x arrangements at price y, and (131 - x) arrangements at price (y + 3)
- Swapped setup: (131 - x) arrangements at price y, and x arrangements at price (y + 3)
Since Type B costs $3 more than Type A, the revenue change depends on which direction we're moving more arrangements:
- We gain $3 for each of the x arrangements that move from Type A price to Type B price
- We lose $3 for each of the (131 - x) arrangements that move from Type B price to Type A price
Revenue change = Gains - Losses = \(3\mathrm{x} - 3(131 - \mathrm{x})\)
Revenue change = \(3\mathrm{x} - 393 + 3\mathrm{x} = 6\mathrm{x} - 393\)
Statement 2 tells us the new revenue > original revenue, which means:
Revenue change > 0
\(6\mathrm{x} - 393 > 0\)
\(6\mathrm{x} > 393\)
\(\mathrm{x} > 65.5\)
Since x must be an integer, x ≥ 66, which means Ruth sold more Type A arrangements than Type B arrangements.
[STOP - Statement 2 is Sufficient!]
The Answer: D
Both statements independently tell us that Ruth sold more Type A arrangements than Type B arrangements.
Answer Choice D: "Each statement alone is sufficient."