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?

A) Yes, this is a valid inference because the 30 families speak for the whole neighborhood

B) Yes, this is a valid inference because she took a random sample of the neighborhood

C) No, this is not a valid inference because she did not take a random sample of the neighborhood

D) No, this is not a valid inference because she asked only 30 families

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?

A) Yes, this is a valid inference because the 30 families speak for the whole neighborhood

B) Yes, this is a valid inference because she took a random sample of the neighborhood

C) No, this is not a valid inference because she did not take a random sample of the neighborhood

D) No, this is not a valid inference because she asked only 30 families

justjm · Answer

The sample is a random sample of "30 neighborhood addresses"
Since n=30, it has reached the optimal sample size. Also it is a random sample. So it is between A and B. When you pick between the two, remember that the representation comes from the random sampling, not the sample size. The sample size only helps in proving the Central Limit Theorem. So now, what do you think?