To find an irrational number between 9 and 11, we can consider the square roots of non-perfect squares within that range.
Let's evaluate the options:
-
\( \sqrt{20} \)
- \( \sqrt{20} \approx 4.47 \) (not between 9 and 11)
-
\( \sqrt{99} \)
- \( \sqrt{99} \approx 9.95 \) (which is between 9 and 11)
-
\( \sqrt{10} \)
- \( \sqrt{10} \approx 3.16 \) (not between 9 and 11)
-
\( \sqrt{100} \)
- \( \sqrt{100} = 10 \) (not an irrational number)
Among these options, \( \sqrt{99} \) is an irrational number that lies between 9 and 11.