Understanding Multi-Source Reasoning
Multi-Source Reasoning (MSR) questions in the GMAT Data Insights (DI) section test your ability to extract, compare, and synthesize information from **multiple sources**. These sources could be:
- Text-based passages
- Tables with numerical data
- Charts, graphs, or diagrams
Each question requires evaluating multiple sources to answer true/false statements, multiple-choice questions, or numeric calculations.
Top Tips for GMAT Multi-Source Reasoning
1. Read the Sources Before the Questions
– Skim through **all sources** first to understand the data relationships.
– Note key figures, definitions, or trends.
2. Look for Contradictions Between Sources
– Some questions test **inconsistencies** between different pieces of data.
– Be careful if two sources provide **similar but different** figures.
3. Organize Information for Comparison
– If multiple tables or charts are provided, write down **key differences**.
– Identify **time periods, categories, and trends** before making calculations.
4. Pay Attention to Units and Percentages
– Check if data is given in **millions vs. thousands** or **percentages vs. raw numbers**.
– Convert numbers where necessary to match formats.
5. Eliminate Extreme or Illogical Answers
– If a choice contradicts **any** source, it’s incorrect.
– If unsure, **cross-reference sources** before selecting an answer.
GMAT DI – Multi-Source Reasoning: Drone Surveillance Classification
📌 Tab-1: Data Guidelines
To classify real-time drone footage events, the system uses unique event identifiers composed of letters and symbols based on the following table:
| Character | Event Type | Description |
|---|---|---|
| P | Perimeter Breach | Unauthorized boundary entry |
| Q | Anomaly Detected | Unknown object detected |
| @ | Signal Loss | Drone communication failure |
| $ | Low Battery | Battery below operational limit |
| # | Environmental Issue | Sudden weather disruption |
| & | Target Identified | High-value target found |
📌 Tab-2: Proposal Alpha
This proposal captures surveillance events with the following components:
- Event Sequence: A 3-character code indicating the sequence of events observed (e.g., PQ$).
- Location Identifier: A 5-digit GPS code (e.g., 74920).
- Timestamp: A 4-digit format in HHMM (e.g., 1145).
📌 Tab-3: Proposal Beta
Proposal Beta builds on Proposal Alpha by adding:
- Dynamic Event Filtering: Events with less than two occurrences in the last hour are ignored.
- Event Validation: Codes with numeric sums exceeding 30 are flagged for validation.
- Error Correction: A checksum character is added to detect transmission errors (calculated by summing all numeric values modulo 5).
Question 1: Membership ID Analysis
Assume the new proposal has been implemented and a member has been assigned an MD of 5678124306541. For each statement about this member, select “Could be true” if the statement could be valid based on the information provided. Otherwise, select “Could not be true.”
| Statement | Could be true / Could not be true |
|---|---|
| The member’s MD includes a hexadecimal hash value in the first two sections. | A. Could be true B. Could not be true |
| The member’s MD contains a total of four alphanumeric characters. | A. Could be true B. Could not be true |
| The member’s registration was at around 2:45 PM. | A. Could be true B. Could not be true |
Question 2: Library Upgrade Proposal
For each criterion mentioned in the library upgrade proposal, select “Explicitly mentioned” if the criterion is specifically referenced in the passage. Otherwise, select “Not explicitly mentioned.”
| Criterion | Explicitly Mentioned / Not Explicitly Mentioned |
|---|---|
| Encryption for all personal information | A. Explicitly mentioned B. Not explicitly mentioned |
| Quick data access while maintaining security | A. Explicitly mentioned B. Not explicitly mentioned |
| Data immutability | A. Explicitly mentioned B. Not explicitly mentioned |
Question 3: Sequence Calculation
How many possible sequences are there for the 3rd and 4th characters of a valid MD under Proposal B, considering the transformation applied to the MD from Proposal A?
- A. 1,024
- B. 1,089
- C. 961
- D. 1,296
- E. 1,048,576
Solutions
Solution to Question 1:
- The MD does not specify a hexadecimal hash value, so the first statement is **”Could not be true.”**
- The MD primarily consists of numbers, and there are **no explicit alphanumeric characters**, making the second statement **”Could not be true.”**
- The timestamp format follows HHMM, and **”245 PM” translates to 1445 in 24-hour format, which is a valid timestamp**, making the last statement **”Could be true.”**
Solution to Question 2:
- The text does not reference **encryption** explicitly, so the first statement is **”Not explicitly mentioned.”**
- The need for **fast but secure data access** is highlighted, making the second statement **”Explicitly mentioned.”**
- The passage does not address **data immutability**, so the third statement is **”Not explicitly mentioned.”**
Solution to Question 3:
- Each character in the MD can have **32 different values**.
- The number of possible sequences for two positions is: \( 32^2 = 1,024 \).
- Thus, the correct answer is **A. 1,024**.