Correct Answer - Option 1 : 48

**Given:**

Average of 5 number = 66.4

Average of the first 2 numbers = 67

Average of last 2 numbers = 75

**Formula used:**

Average = Sum of numbers/Number of units

**Calculation:**

Sum of all 5 numbers = 66.4 × 5 = 332

Sum of first 2 numbers = 2 × 67 = 134

Sum of last 2 numbers = 2 × 75 = 150

Middle number = 332 – (134 + 150)

⇒ 332 – 284

⇒ 48

**∴ The middle number is 48**