Answer:
greater than or equal to 9.48 feet
Explanation:
The question is, what is the value of √(90)?
Factor 90. You don't have to do this but I suspect it could be one of the answers.
90: 18*5
90:3 * 3 * 2 * 5
√(90) = √(3 * 3 * 2 * 5) Take one of the 3s outside the square root sign. Take the root of what is left.
3√2*5 = 3√10
√10 = 3.16
So the wall must be greater than or equal to 3 * 3.16 ≥ 9.48 feet.