it's estimated that 750 students in the whole school dislike the 8:30am start time.
Step-by-step explanation:
Since 30 of the 40 students said "no", it means 30/40, or 3/4 of the random sample disliked the 8:30am start time. Multiply this by the whole population: 1,000 × (3/4) = 750.
Another way to check this is using 10/40 = .25 and doing 1000x.25 = 250 (the amount of students who liked it). Then subtract from whole population and it's 750.
