Find the missing term in the sequence: 6, __, 21, 33, 48.

Introduction / Context:
We identify the pattern that generates this sequence. Many aptitude sequences use increasing differences with a fixed step. We infer the missing term consistently with later terms.

Given Data / Assumptions:

• Sequence: 6, __, 21, 33, 48.
• Likely pattern: differences increasing by a constant.

Concept / Approach:

• Let the missing term be x. Differences: x−6, 21−x, 12, 15.
• If differences increase by 3 each time: (x−6), (21−x), 12, 15 with step +3.

Step-by-Step Solution:

Verification / Alternative check:
The +3 increase in differences is consistent across the entire sequence after inserting 12; pattern holds strictly.

Why Other Options Are Wrong:

• 14, 18, 20: Break the constant +3 step in differences.
• None of these: Not applicable since 12 works perfectly.

Common Pitfalls:

• Guessing without checking later terms.
• Assuming constant difference instead of increasing difference.

Final Answer:
12