Explanation:

Certainly! Let me explain step by step:

- The total sum of all twelve numbers is \(12 \times 58 = 696\).

- The sum of the first five numbers is \(5 \times 56 = 280\).

- The sum of the next four numbers is \(4 \times 60 = 240\).

- The sum of the remaining three numbers (10th, 11th, and 12th) is \(696 - 280 - 240 = 176\).

- Let's denote the 11th number as \(x\).

- The 10th number is \(x + 4\), and the 12th number is \(x + 1\).

- So, \(x + 4 + x + x + 1 = 176\).

- This equation simplifies to \(3x + 5 = 176\).

- Solving for \(x\), we get \(3x = 171\), therefore \(x = 57\).

- The 10th number \(= x + 4 = 61\).

- The 12th number \(= x + 1 = 58\).

- The average of the 10th and 12th numbers \((61 + 58) / 2 = 59.5\).

- Option 2: 59.5