a) Her reasoning is not correct. b) Answers can be decimals or fractions.
Work Step by Step
a) The correct range of answers is $a \geq 5.4$, not $a\geq6$. She only looked at whole numbers, not decimals, so that's why her reasoning is not correct. b) As stated, decimals or fractions can be answers. Thus, that's why substituting values into the inequality doesn't guarantee a correct solution.