A monthly magazine receives revenue from exactly 3 sources: advertising, newsstand sales, and subscriptions. By what percent must subscription revenue...
GMAT Data Sufficiency : (DS) Questions
A monthly magazine receives revenue from exactly 3 sources: advertising, newsstand sales, and subscriptions. By what percent must subscription revenues rise in order to offset recent decreases in advertising revenue and newsstand sales?
- Advertising revenue decreased by \(\mathrm{25\%}\) and newsstand sales decreased by \(\mathrm{40\%}\).
- Before the recent decreases, the total revenue from advertising and newsstand sales was \(\mathrm{\$35,500}\) per month.
Understanding the Question
We need to find a specific percentage: by what percent must subscription revenues rise to offset the decreases in advertising and newsstand revenues?
What We Need to Determine
The question asks for a precise percentage value. To answer this, we need:
- The total dollar amount that decreased (from advertising and newsstand combined)
- The current subscription revenue (this will be our percentage base)
The required percentage = \((\mathrm{Total\,decrease\,amount} ÷ \mathrm{Current\,subscription\,revenue}) \times 100\%)\)
Key Insight
Here's the critical insight: We're looking for a percentage, which requires both a numerator (the decrease amount) and a denominator (subscription revenue). Without either piece, we cannot determine the percentage. Pay special attention to whether we ever learn anything about subscription revenue.
Analyzing Statement 1
Statement 1 tells us: Advertising revenue decreased by \(25\%\) and newsstand sales decreased by \(40\%\).
This gives us the percentage decreases, but notice what's missing:
- We don't know the original dollar amounts for advertising or newsstand revenues
- We have no information about subscription revenue whatsoever
Let's test different scenarios to confirm we can't determine a unique answer:
Scenario 1: Suppose advertising was originally \(\$20,000\) and newsstand was \(\$10,000\)
- Advertising decrease: \(25\% \times \$20,000 = \$5,000\)
- Newsstand decrease: \(40\% \times \$10,000 = \$4,000\)
- Total decrease to offset: \(\$9,000\)
- But we still don't know subscription revenue!
Scenario 2: Suppose advertising was originally \(\$25,000\) and newsstand was \(\$5,000\)
- Advertising decrease: \(25\% \times \$25,000 = \$6,250\)
- Newsstand decrease: \(40\% \times \$5,000 = \$2,000\)
- Total decrease to offset: \(\$8,250\)
- Again, no subscription revenue information!
Even if we could somehow determine the exact decrease amount, without knowing subscription revenue, we cannot calculate what percentage of it equals that decrease.
Statement 1 is NOT sufficient.
[STOP - Insufficient!] 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: Before the recent decreases, the total revenue from advertising and newsstand sales was \(\$35,500\) per month.
This gives us the combined pre-decrease amount, but we're still missing:
- How the \(\$35,500\) splits between advertising and newsstand
- What percentage or dollar amounts the revenues decreased by
- Most crucially: the subscription revenue
Without knowing how much the revenues decreased or what the subscription revenue is, we cannot determine the required percentage increase.
Statement 2 is NOT sufficient.
[STOP - Insufficient!] This eliminates choice B.
Combining Both Statements
Now let's see what we learn from both statements together:
- From Statement 2: Advertising + Newsstand = \(\$35,500\) (before decreases)
- From Statement 1: Advertising decreased by \(25\%\), newsstand decreased by \(40\%\)
Here's where students often get trapped. Even though we don't know the exact split of the \(\$35,500\), we might think we're getting closer. Let's test this carefully:
Test Case 1: If advertising was \(\$20,000\) and newsstand was \(\$15,500\):
- Advertising decrease: \(25\% \times \$20,000 = \$5,000\)
- Newsstand decrease: \(40\% \times \$15,500 = \$6,200\)
- Total decrease: \(\$11,200\)
Test Case 2: If advertising was \(\$25,000\) and newsstand was \(\$10,500\):
- Advertising decrease: \(25\% \times \$25,000 = \$6,250\)
- Newsstand decrease: \(40\% \times \$10,500 = \$4,200\)
- Total decrease: \(\$10,450\)
So different splits give us different total decreases (\(\$11,200\) vs \(\$10,450\)). But here's the crucial point that makes this problem unsolvable: We still have absolutely no information about subscription revenue!
Whether the total decrease is \(\$11,200\), \(\$10,450\), or any other amount, without knowing the subscription revenue base, we cannot calculate what percentage of it this represents.
Think of it this way: If subscription revenue is \(\$5,000\), then a \(\$10,450\) decrease requires a \(209\%\) increase. But if subscription revenue is \(\$50,000\), then the same \(\$10,450\) decrease requires only a \(20.9\%\) increase. Since we have no information about subscription revenue, we cannot determine the percentage.
The statements together are NOT sufficient.
[STOP - Insufficient!] This eliminates choice C.
The Answer: E
The statements together are not sufficient because we never receive any information about subscription revenue, which is the essential denominator for calculating the required percentage increase.
Answer Choice E: The statements together are not sufficient.