AP Stats Unit 6

Interpreting Confidence Interval

We can be _% confident that in the population of all (context), the proportion that (have the quality in context) is between _ and _.

Interpreting Confidence Level

If the (context) selects many random samples of (n) (individuals) and constructs a _% confidence interval using each sample, then about _% of these intervals will capture the true proportion of all (individuals) that (quality in context).

Answering FRQs for Building Confidence Intervals for a Population Proportion

• State interval you intend to build

  • For population proportion use “one-sample z-interval for population proportion”

• State formula

  

• Requirements have been met

  • Random sample

  • Less than 10%

  • Large enough sample size (10 checks)

• Calculate interval

Margin of Error (M) or (E)

Point estimate to either the upper or lower bound

Subtract higher from lower, divide by 2

Point Estimate

Center

Add, divide by 2

Width

Interval is the size of the entire interval

2 times margin of error

Determining the Sample Size n

Always round up

Determining the Sample Size n

Always round up