Question 1

Suppose a survey was done this year to find out what percentage of all American households own a bread machine. Out of their random sample of 1,000 American households, 317 reported they own a bread machine. The margin of error for this survey was plus or minus 3 percentage points. Based on those results, what percentage of American households own a bread machine?

Answer

Exactly 31.7%

We can be 95% certain that it's between 28.7% and 34.7%

We can be 95% certain that it's between 25.7% and 37.7%

We can be 95% certain that it's between 30.2% and 32.9%

None of the above.

Question 2

Suppose three years ago, a similar poll with a 3 percentage point error margin showed 29.5% of American households owned a bread machine. Based on the results of the new survey described in the first question, what can you conclude (with 95% confidence) about the population of all American households now compared with three years ago?

Answer

A larger proportion of American households own a bread machine now compared to three years ago.

The proportion of American households who own a bread machine has not significantly changed from three years ago.

A smaller proportion of American households own a bread machine now compared to three years ago.

More than 61% of American households have bought bread machines in the past three years.