Confidence Interval
Difference in Proportions

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1) Assumptions & Conditions To State & Check
1. Independent random samples are drawn from the two separate populations.
2. Each of the following 4 conditions need to be stated and checked:

2) General Formula

*Hints:
1) Strongly suggested to use 2-PropZInt function in the TI-83/84 first, then work backwards to recreate the formula with appropriate numbers.
2) For AP Students - the AP formula sheet provides the following formulas to greatly help in recreating the above formula during the exam. Use the top formula (replacing p for p-hat) for confidence intervals and the bottom formula for a hypothesis test.

3) Interpretation - EXAMPLE - 95% Confidence Interval

Based on the data, I can be 95% confident that the difference in the proportion of population 1 and the proportion of population 2 falls between the 0.57 and 0.59.  

(MAKE SURE TO MODIFY THIS STATEMENT SO THAT IT REFLECTS THE CONTEXT OF THE PROBLEM)

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