To find how many irrational numbers are between \( \sqrt{11} \) and \( \sqrt{17} \), we first calculate the numerical values of these square roots.
- \( \sqrt{11} \) is approximately \( 3.3166 \)
- \( \sqrt{17} \) is approximately \( 4.1231 \)
The interval between \( \sqrt{11} \) and \( \sqrt{17} \) is approximately from \( 3.3166 \) to \( 4.1231 \).
Within any interval of real numbers, there are infinitely many irrational numbers. This is because between any two real numbers (rational or irrational), you can always find another rational or irrational number.
Thus, the correct answer is:
an infinite number.