How many 7s are there in the following number series which are preceded by 9 and also followed by 6?
7 8 9 7 6 5 3 4 2 8 9 7 2 4 5 9 2 9 7 6 4 7

Options

A. two
B. three
C. four
D. five

Explanation

To solve the problem of how many 7s are there in the given number series that are preceded by 9 and followed by 6, we will follow these steps:

### Step 1: Write down the number series
The given number series is:
7, 8, 9, 7, 6, 5, 3, 4, 2, 8, 9, 7, 2, 4, 5, 9, 2, 9, 7, 6, 4, 7

### Step 2: Identify the pattern
We need to look for the number 7 that is preceded by 9 and followed by 6. This means we are looking for the sequence "9, 7, 6".

### Step 3: Scan the series for the pattern
Now, we will scan through the series to find occurrences of the pattern "9, 7, 6".

1. Start from the beginning of the series:
- The first number is 7 (not preceded by 9).
- The second number is 8 (not preceded by 9).
- The third number is 9 (check the next number).
- The fourth number is 7 (check the next number).
- The fifth number is 6 (we have found one occurrence of "9, 7, 6").

2. Continue scanning:
- The sixth number is 5 (not preceded by 9).
- The seventh number is 3 (not preceded by 9).
- The eighth number is 4 (not preceded by 9).
- The ninth number is 2 (not preceded by 9).
- The tenth number is 8 (not preceded by 9).
- The eleventh number is 9 (check the next number).
- The twelfth number is 7 (check the next number).
- The thirteenth number is 2 (not followed by 6).
- The fourteenth number is 4 (not preceded by 9).
- The fifteenth number is 5 (not preceded by 9).
- The sixteenth number is 9 (check the next number).
- The seventeenth number is 2 (not followed by 6).
- The eighteenth number is 9 (check the next number).
- The nineteenth number is 7 (check the next number).
- The twentieth number is 6 (we have found another occurrence of "9, 7, 6").

3. Continue scanning:
- The twenty-first number is 4 (not preceded by 9).
- The twenty-second number is 7 (not preceded by 9).

### Step 4: Count the occurrences
From our scan, we found two occurrences of the pattern "9, 7, 6":
1. The first occurrence is at positions (3, 4, 5).
2. The second occurrence is at positions (11, 12, 13).

### Final Answer
Thus, the total number of 7s that are preceded by 9 and followed by 6 in the series is **2**.

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