MARGIN OF ERROR

Honors Advanced Algebra

Presentation 1-7

RETURN QUIZ The mean of the quiz grades was 33.77,

and the standard deviation was 4.11.

The mean of Algebra grades is currently 86.85, and the standard deviation is 8.69.

MARGIN OF ERROR The margin of error of a random sample

defines an interval, centered on the sample percent, in which the population percent is most likely to lie.

EXAMPLE 1 After a 1000 person poll, a polling

organization reports that 58% of citizens plan to vote for candidate A with a margin of error of ± 3%.

What is the range of possible vote percentages for candidate A?

Does this leave any doubt as to who will win the election?

EXAMPLE 2 Students at a high school will vote on a

proposal to start classes later. According to a sample survey, 54% of the students agree and 46% disagree with the proposal. The margin of error is ±5%.

What is the range of possible percents of agreement?

Can we say with certainty that the proposal will pass?

HOMEWORK Pg 49-50, #6-7, 20-22