600, 125, 30, 13, 7.2, 6.44, 6.288

Options

A. 6
B. 10
C. 15
D. None of these

Explanation

To solve the problem of identifying the wrong number in the series: 600, 125, 30, 13, 7.2, 6.44, 6.288, we will analyze the pattern of the series step by step.

### Step 1: Identify the pattern
The series appears to be decreasing, and it seems that each number is derived from the previous number through division and possibly addition.

### Step 2: Analyze the first two numbers
Starting with the first number:
- From 600 to 125:
- If we divide 600 by 5, we get 120.
- Then, adding 5 gives us 125.

**Calculation**:
\[ 600 \div 5 = 120 \quad \text{and} \quad 120 + 5 = 125 \]

### Step 3: Analyze the second to third numbers
- From 125 to 30:
- Dividing 125 by 5 gives us 25.
- Adding 5 gives us 30.

**Calculation**:
\[ 125 \div 5 = 25 \quad \text{and} \quad 25 + 5 = 30 \]

### Step 4: Analyze the third to fourth numbers
- From 30 to 13:
- Dividing 30 by 5 gives us 6.
- Adding 7 gives us 13.

**Calculation**:
\[ 30 \div 5 = 6 \quad \text{and} \quad 6 + 7 = 13 \]

### Step 5: Analyze the fourth to fifth numbers
- From 13 to 7.2:
- Dividing 13 by 5 gives us 2.6.
- Adding 4.6 gives us 7.2.

**Calculation**:
\[ 13 \div 5 = 2.6 \quad \text{and} \quad 2.6 + 4.6 = 7.2 \]

### Step 6: Analyze the fifth to sixth numbers
- From 7.2 to 6.44:
- Dividing 7.2 by 5 gives us 1.44.
- Adding 5 gives us 6.44.

**Calculation**:
\[ 7.2 \div 5 = 1.44 \quad \text{and} \quad 1.44 + 5 = 6.44 \]

### Step 7: Analyze the sixth to seventh numbers
- From 6.44 to 6.288:
- Dividing 6.44 by 5 gives us 1.288.
- Adding 5 gives us 6.288.

**Calculation**:
\[ 6.44 \div 5 = 1.288 \quad \text{and} \quad 1.288 + 5 = 6.288 \]

### Step 8: Identify the wrong number
Upon analyzing the series, we notice that the transition from 30 to 13 does not follow the same pattern as the others. The expected number after dividing 30 by 5 should have been 6, not 13. Therefore, the wrong number in the series is **13**.

### Final Answer
The wrong number in the series is **13**.

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