Angela wants to know how many families in her neighborhood plan to attend the parade. She puts all 120 of the neighborhood addresses in a hat and draws a random sample of 30 addresses. She then asks those families if they plan to attend the parade. She finds that 40% of the families plan to attend the parade. She claims that 40% of the neighborhood families would be expected to attend the parade. Is this a valid inference?
Yes, this is a valid inference because the 30 families speak for the whole neighborhoo Yes, this is a valid inference because she took a random sample of the neighborhood

Question

Angela wants to know how many families in her neighborhood plan to attend the parade. She puts all 120 of the neighborhood addresses in a hat and draws a random sample of 30 addresses. She then asks those families if they plan to attend the parade. She finds that 40% of the families plan to attend the parade. She claims that 40% of the neighborhood families would be expected to attend the parade. Is this a valid inference?
  Yes, this is a valid inference because the 30 families speak for the whole neighborhoo Yes, this is a valid inference because she took a random sample of the neighborhood

anonymous · Answer

No, this is not a valid inference because she did not take a random sample of the neighborhood

 No, this is not a valid inference because she asked only 30 families

tkhunny · Answer

30 out of 120, selected randomly?  WOW!  A 25% sample!  How could it not be a valid inference?

I don't really like any of the answers, but the second one seems the closest.  It should say that is was a LARGE ENOUGH random sample.