In each of the following questions, four numbers are given. Out of these three are alike in some way but rest one is different. Choose the one which is different from the other.

Options

A. 10
B. 11
C. 15
D. 16

Answer

To solve the problem of identifying the number that is different from the others among the four given numbers (10, 11, 15, and 16), we will analyze each number based on whether they are prime or composite.

### Step-by-Step Solution:

1. **Identify the Numbers:**
- The numbers given are 10, 11, 15, and 16.

2. **Determine the Nature of Each Number:**
- **10:**
- Factors: 1, 2, 5, 10
- Since it has more than two factors, 10 is a composite number.
- **11:**
- Factors: 1, 11
- Since it has exactly two factors, 11 is a prime number.
- **15:**
- Factors: 1, 3, 5, 15
- Since it has more than two factors, 15 is a composite number.
- **16:**
- Factors: 1, 2, 4, 8, 16
- Since it has more than two factors, 16 is a composite number.

3. **Classify the Numbers:**
- Composite Numbers: 10, 15, 16
- Prime Number: 11

4. **Identify the Odd One Out:**
- Among the four numbers, 10, 15, and 16 are composite numbers, while 11 is the only prime number.

5. **Conclusion:**
- Therefore, the number that is different from the others is **11**.