Question

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

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

Answer:

D. 4

There are 4 such odd digits in the given series.

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We are looking for a specific 3-digit combination that fits this pattern:
$\text{Even Digit} \rightarrow \textbf{Odd Digit (Target)} \rightarrow \text{Odd Digit}$

Let's scan the full series step-by-step from left to right to find all occurrences:
5 6 9 7 4 5 3 7 8 3 4 2 1 5 7 9 8 1 2 3 4 3 6 2 1 5 7

1. 6 - 9 - 7: 6 (Even) $\rightarrow$ 9 (Odd) $\rightarrow$ 7 (Odd) $\rightarrow$ Match

2. 4 - 5 - 3: 4 (Even) $\rightarrow$ 5 (Odd) $\rightarrow$ 3 (Odd) $\rightarrow$ Match

3. 8 - 3 - 4: 8 (Even) $\rightarrow$ 3 (Odd) $\rightarrow$ 4 (Even) $\rightarrow$ No match.

4. 2 - 1 - 5: 2 (Even) $\rightarrow$ 1 (Odd) $\rightarrow$ 5 (Odd) $\rightarrow$ Match

5. 2 - 3 - 4: 2 (Even) $\rightarrow$ 3 (Odd) $\rightarrow$ 4 (Even) $\rightarrow$ No match.

6. 6 - 2 - 1: 6 (Even) $\rightarrow$ 2 (Even) $\rightarrow$ 1 (Odd) $\rightarrow$ No match.

7. 2 - 1 - 5: 2 (Even) $\rightarrow$ 1 (Odd) $\rightarrow$ 5 (Odd) $\rightarrow$ Match

Verified Matches:

• 9 (in 6-9-7)

• 5 (in 4-5-3)

• 1 (in 2-1-5, first instance)

• 1 (in 2-1-5, second instance near the end)