AP Statistics : How to estimate margins of errors
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Example Questions
Example Question #1 : How To Estimate Margins Of Errors
The next local election is predicted to have a 
If you remember the required formula, this problem is rather simple. Plug in the given numbers and simplify:
If you don't remember the formula, this problem is more challenging. Your best bet in this case is to construct the confidence interval and rearrange to solve for the required sample size.
Example Question #1 : Estimation
When dealing with confidence intervals, the margin of error gets smaller when z* gets ________ and n gets _________.
smaller . . . larger
There is no way to affect the margin of error in confidence intervals
smaller . . . smaller
larger . . . smaller
larger . . . larger
smaller . . . larger
For confidence intervals, a small margin of error is preferred, as it indicates that the parameter of interest has been narrowed down to a precise interval. Having a large sample population to work from as well as a small z* (z* gets smaller as the confidence level percent gets lower) can help obtain a small margin of error.
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