Question

How many odd numbers are there in the sequence, each of which is immediately followed by an odd number? \[ 5 3 4 7 1 9 6 5 3 4 6 9 3 7 6 4 1 6 5 2 4 4 3 6 9 4. \]

• A. 4
• B. 6
• C. 5
• D. 3

Hint:

To solve problems like this, carefully examine the sequence for odd-numbered digits and check if each odd number is immediately followed by another odd number.

Answer 1

The Correct Option is B

We are given the sequence of numbers:
\[ 5 3 4 7 1 9 6 5 3 4 6 9 3 7 6 4 1 6 5 2 4 4 3 6 9 4. \] Our task is to find how many odd numbers are immediately followed by another odd number in this sequence.
Step 1: Identify the odd numbers in the sequence
The odd digits are: 1, 3, 5, 7, and 9. We need to find instances where an odd number is immediately followed by another odd number.
Step 2: Analyze the sequence Let’s go through the sequence step by step:
- 5 is followed by 3 (odd-odd pair).
- 3 is followed by 7 (odd-odd pair).
- 7 is followed by 1 (odd-odd pair).
- 9 is followed by 6 (not an odd-odd pair).
- 6 is followed by 5 (not an odd-odd pair).
- 5 is followed by 3 (odd-odd pair).
- 3 is followed by 4 (not an odd-odd pair).
- 6 is followed by 9 (not an odd-odd pair).
- 9 is followed by 3 (odd-odd pair).
- 3 is followed by 7 (odd-odd pair).
- 7 is followed by 6 (not an odd-odd pair).
- 6 is followed by 4 (not an odd-odd pair).
- 4 is followed by 1 (not an odd-odd pair).
- 1 is followed by 6 (not an odd-odd pair).
- 6 is followed by 5 (not an odd-odd pair).
- 5 is followed by 2 (not an odd-odd pair).
- 2 is followed by 4 (not an odd-odd pair).
- 4 is followed by 3 (not an odd-odd pair).
- 3 is followed by 4 (not an odd-odd pair).
Step 3: Count the odd-odd pairs
From the sequence, the odd-odd pairs are:
1. 5 followed by 3
2. 3 followed by 7
3. 7 followed by 1
4. 5 followed by 3
5. 9 followed by 3
6. 3 followed by 7
Thus, there are 6 odd numbers that are immediately followed by an odd number.
Final Answer:
Therefore, the correct answer is \( \boxed{6} \).