Answer: At least 96 OR 340 students.
Step-by-step explanation:
1) Since we know that at least 96 students of the survey have at least one sibling, it is safe to assume that 96 students of the total 425 students have at least one sibling.
2) Since we know that 80% of respondents to the survey have at least one sibling, we could apply that percentage to the whole school:
80% × 425 students = 340 students.
Hence, we could conclude that 340 students have at least one sibling.