Ch4. GMAT Data Insights — Data Sufficiency & Analytical Reasoning

Data Insights Overview

GMAT Focus Edition Data Insights: 20 questions, 45 minutes, calculator available.

Question types:

• Data Sufficiency (DS): ~8 questions
• Table Analysis: ~4 questions
• Graphics Interpretation: ~4 questions
• Multi-Source Reasoning: ~4 questions

---

Data Sufficiency: GMAT’s Unique Question Type

DS questions ask you to determine whether given conditions are sufficient to answer a question — not to solve the problem itself.

The 5 Fixed Answer Choices

Every DS question has the same 5 choices:

(A) Statement (1) ALONE is sufficient, but statement (2) alone is not
(B) Statement (2) ALONE is sufficient, but statement (1) alone is not
(C) BOTH statements TOGETHER are sufficient, but NEITHER alone is
(D) EACH statement ALONE is sufficient
(E) Statements (1) and (2) TOGETHER are NOT sufficient

DS Golden Rules

1. Test each statement independently: When evaluating (1), completely ignore (2)
2. Sufficiency ≠ a unique numerical answer: For yes/no questions, consistent YES (or consistent NO) = sufficient
3. The most common trap: A condition that looks sufficient but has multiple possible solutions

DS Example

Is x positive?
(1) x² = 9
(2) x + 5 > 3

• (1): x = 3 or x = −3 → NOT sufficient (could be positive or negative)
• (2): x > −2 → NOT sufficient alone (x could be −1, 0, or positive)
• Together: x must be 3 → SUFFICIENT → Answer: C

---

Table Analysis

View a sortable spreadsheet and determine whether each statement is TRUE or FALSE.

Strategy:

• Use the sort feature to organize data before answering
• Verify each statement independently
• Watch for: proportions, averages from totals, extreme values

---

Graphics Interpretation

View a chart (bar, line, scatter, pie) and fill in blanks using the data.

Chart Type	What to Look For
Bar chart	Absolute comparisons, trends
Line chart	Rate of change (slope), crossover points
Scatter plot	Correlation direction and outliers
Pie chart	Proportions summing to 100%

---

Multi-Source Reasoning

Multiple tabs (text + table + chart combinations) require synthesizing information across sources.

Strategy:

1. Quickly scan all tabs to know what’s where
2. Read the question, then go directly to the relevant source
3. Look for: contradictions between sources, data that only exists in one source

---

Statistics Quick Reference

Concept	Formula/Definition
Mean	∑x / n
Median	Middle value when sorted
Variance	∑(x−μ)² / n
Standard deviation	√variance
Correlation	−1 ≤ r ≤ +1 (r=0: no linear correlation)
Percentile	% of data at or below the value

---

Chapter 5 Preview

Next: GMAT Test Strategy — understanding CAT adaptive scoring, section pacing, and the optimal approach to difficult questions.