Question

Refer to the following series and answer the question (all numbers are single digit numbers only). (Left) 3 5 2 3 4 3 1 5 7 9 5 8 5 7 5 4 2 3 6 2 1 3 7 6 9 7 4 (Right) How many such even digits are there each of which is immediately preceded by an odd digit and also immediately followed by an even digit?

• A. 4
• B. 0
• C. 3
• D. 2

Answer 1

Answer:

D. 2

There are 2 such even digits in the series that meet the criteria.

The Criteria Explained

We are looking for a pattern that matches: Odd Digit → Even Digit → Even Digit

Let's filter out every even digit in the series and look at its immediate neighbors:

1. ... 5 2 3 ... → Preceded by 5 (odd), followed by 3 (odd).

2. ... 3 4 3 ... → Preceded by 3 (odd), followed by 3 (odd).

3. ... 5 8 5 ... → Preceded by 5 (odd), followed by 5 (odd).

4. ... 5 4 2 ... → Match 1! The even digit 4 is preceded by 5 (odd) and followed by 2 (even).

5. ... 4 2 3 ... → Preceded by 4 (even), followed by 3 (odd).

6. ... 3 6 2 ... → Match 2! The even digit 6 is preceded by 3 (odd) and followed by 2 (even).

7. ... 6 2 1 ... → Preceded by 6 (even), followed by 1 (odd).

8. ... 7 6 9 ... → Preceded by 7 (odd), followed by 9 (odd).

9. ... 7 4 (End) → Preceded by 7 (odd), but it is the last element so it is not followed by any digit.

Summary of Matches found:

• 5 - 4 - 2

• 3 - 6 - 2