#### Answer

$s\geq475$

#### Work Step by Step

The phrase, "at least 475 students" implies that at least 475 students attended the orchestra. The number of students could be 475 or more, but not less. This translates to greater than or equal to ($\geq$).
Let $s$ be the number of students who attended.
The number of students who attended is greater than or equal to 475.
Therefore, the correct inequality for this statement is $s\geq475$.