To find an irrational number between 9 and 11, we can look at the examples you provided:
- \( \sqrt{100} = 10 \) (not irrational, it's a whole number)
- \( \sqrt{10} \) (approximately \( 3.162 \), not between 9 and 11)
- \( \sqrt{99} \) (approximately \( 9.95 \), which is between 9 and 11 and is irrational)
- \( \sqrt{20} \) (approximately \( 4.472 \), not between 9 and 11)
From this, the irrational number between 9 and 11 is:
Response: \( \sqrt{99} \)