Question

Catherine finds that in a randomly selected sample of 500 families in her home town, 45% own at least one computer. Her research shows that there are a total of 35,000 families in her town.
Which statements are true?
Select each correct answer.
Since her sample was randomly selected, she can reasonably infer that about 45% of the 35,000 families in her town own at least one computer.
To estimate the percentage well, she would need to collect data for all 35,000 families.
If she collected data for a random sample of 1000 families in her home town, then that percentage would be a better estimate for the percentage of all 35,000 families that own a computer.
Since her sample was only 500 families, it is not possible that the percentage is a good estimate for the percentage of all 35,000 families that own a computer.

Answer 1

I think that with a sample of 500 her margin of error  is  about 5% and it won't be much less for a sample of 1000  It would be better though. 
Not sure about the first statement  The fact that its randomly selected doesnt mean  the inference is valid (especially if the sample size was small).
The next 2 are true.
The last one is false.