Explanation:

To find the average of all even numbers between 11 and 27:

- Identify even numbers within this range: 12, 14, 16, 18, 20, 22, 24, and 26.

- Count the even numbers: 8 numbers.

- Sum of these numbers: 12 + 14 + 16 + 18 + 20 + 22 + 24 + 26 = 152.

- Calculate the average: 152 divided by 8 = 19.

- The answer is Option 3: 19.

Statement review:

- Option 1: 20 - This is incorrect. The actual average is less than this.

- Option 2: 17.5 - This is incorrect. The actual average is higher.

- Option 3: 19 - This is indeed the correct average.

- Option 4: 18 - This is incorrect as the calculated average is higher.