Suppose a survey was done this year to find out what percent

Suppose a survey was done this year to find out what percentage of all Americans own a bread machine. Out of their random sample of 1,000 Americans, 317 own a bread machine. The margin of error (with high confidence) for this survey was plus or minus 3%.

What proportion of the entire American population owns a bread machine, based on these results?

Suppose three years ago, 29% of Americans owned a bread machine. Based on the results of this current survey, what would you conclude (with high confidence) about the population of all Americans now compared with three years ago?

Solution

proportion =317/1000=0.317, so 31.7 %

since margin of error is 3 % so based on these results 28.7 to 34.7 % Americans own a bread machine.

since three years ago 29% of Americans owned a bread machine. This 29% lies in the above limit 28.7 to 34.7 %. so we can conclude that the proportion of Americans who own a bread machine has not significantly changed from three years ago.