Lesson 2.9: Data Sufficiency & Series Completion

Introduction:
Data sufficiency and series completion questions are common in SSC exams. They test analytical skills and the ability to determine if the given information is adequate to answer a question.

1. Data Sufficiency

• Definition: Determine if the provided statements are enough to answer a question.

• Common Patterns:

  1. Statement 1 alone sufficient?

  2. Statement 2 alone sufficient?

  3. Both together sufficient?

  4. Not sufficient even together?

• SSC Tips:

  • Analyze each statement independently.

  • Avoid unnecessary calculations.

  • Use elimination method to quickly decide sufficiency.

2. Series Completion

• Definition: Identify the missing term in a series based on the pattern.

• Types of Series:

  1. Number series: Arithmetic, geometric, squares/cubes, mixed patterns

  2. Alphabet series: Forward, backward, alternating letters

  3. Mixed series: Combination of numbers and letters

• SSC Tips:

  • Identify the pattern clearly before guessing.

  • Check difference, ratio, or positional changes.

  • For mixed series, separate numbers and letters to find patterns.

3. Example

Data Sufficiency Question:
Question: Find x.

1. x + 5 = 12

2. x – 3 = 4

• Solution:
  Statement 1 → x = 7 ✅
  Statement 2 → x = 7 ✅
  Both sufficient individually.

Series Completion Question:
Series: 2, 4, 8, 16, ? → Next term = 32 (×2 pattern)

4. Practice Questions

1. Data Sufficiency: Solve y from

   1. 3y + 6 = 15

   2. 2y – 4 = 10

2. Series Completion: 5, 10, 20, 40, ?

3. Data Sufficiency: Find a + b from

   1. a – b = 4

   2. a = 10

4. Series Completion: A, C, F, J, ?

5. Data Sufficiency: Find x² from

   1. x = 3

   2. x² + 1 = 10