To find an irrational number between 9 and 11 from the options given, we can analyze each option:
-
Square root of 20:
\(\sqrt{20} \approx 4.47\) (not between 9 and 11) -
Square root of 99:
\(\sqrt{99} \approx 9.95\) (this is between 9 and 11 and is irrational) -
Square root of 100:
\(\sqrt{100} = 10\) (this is rational) -
Square root of 10:
\(\sqrt{10} \approx 3.16\) (not between 9 and 11)
The only option that is an irrational number between 9 and 11 is square root of 99.