If Pei ordered a total of 63 bottles of cola, root beer, and ginger ale for a party, how many...
GMAT Data Sufficiency : (DS) Questions
If Pei ordered a total of \(63\) bottles of cola, root beer, and ginger ale for a party, how many bottles of cola did she order?
- The number of bottles of root beer that Pei ordered was \(80%\) of the number of bottles of ginger ale that she ordered.
- The number of bottles of cola that Pei ordered was \(75%\) of the total number of bottles of root beer and ginger ale that she ordered.
Understanding the Question
We need to find the exact number of cola bottles that Pei ordered.
Given Information
- Total bottles ordered = 63
- Three types: cola (C), root beer (R), and ginger ale (G)
- \(\mathrm{C + R + G = 63}\)
What We Need to Determine
For this value question to be sufficient, we need to be able to calculate a unique numerical value for C (the number of cola bottles).
Key Insight
Since we have 3 unknowns (C, R, G) and only 1 equation from the setup, we need 2 more independent equations to solve for a unique value. Each statement will provide at most one additional constraint, so let's see if either statement alone gives us enough information.
Analyzing Statement 1
Statement 1 tells us: The number of root beer bottles was 80% of the number of ginger ale bottles.
This gives us the relationship: \(\mathrm{R = 0.8G}\)
Now we have:
- \(\mathrm{C + R + G = 63}\)
- \(\mathrm{R = 0.8G}\)
Substituting the second equation into the first:
\(\mathrm{C + 0.8G + G = 63}\)
\(\mathrm{C + 1.8G = 63}\)
We still have one equation with two unknowns (C and G). We cannot determine unique values for either variable.
For example:
- If G = 10, then C = 45
- If G = 20, then C = 27
- Different values of G give different values of C
Statement 1 is NOT sufficient.
This eliminates choices A and D.
Analyzing Statement 2
Now let's forget Statement 1 completely and analyze Statement 2 independently.
Statement 2 tells us: The number of cola bottles was 75% of the total number of root beer and ginger ale bottles combined.
This gives us: \(\mathrm{C = 0.75(R + G)}\)
Since we know \(\mathrm{C + R + G = 63}\), we can express \(\mathrm{R + G = 63 - C}\)
Substituting this into our Statement 2 equation:
\(\mathrm{C = 0.75(63 - C)}\)
\(\mathrm{C = 47.25 - 0.75C}\)
\(\mathrm{C + 0.75C = 47.25}\)
\(\mathrm{1.75C = 47.25}\)
\(\mathrm{C = 27}\)
We get a unique value: C = 27 bottles of cola.
[STOP - Sufficient!]
Statement 2 is sufficient.
This eliminates choices C and E.
The Answer: B
Statement 2 alone is sufficient because it provides the exact relationship needed to solve for C uniquely, while Statement 1 alone leaves us with two unknowns and insufficient constraints.
Answer Choice B: "Statement 2 alone is sufficient, but Statement 1 alone is not sufficient."