Question 1186947: In a survey of 1010 adults in a country,77% said being able to speak the language is at the core of national identity. The survey's margin of error is +/- 3.2%.
Confidence interval for the proportion is (0.738, 0.802)
Please determine:
The interval is a ?% confidence interval?
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! The difference of each endpoint from the mean is 0.032
0.032=z(sqrt(.77*.23)/1010); sqrt term=0.01324
z=-.032/0.01324=2.416
that is prob=0.0078 on each side, 0.0156 altogether, orange 98.44% CI.
This won't be exact because 77% will give 777.7 which can't be the numerator, it will have to be 778, and that will change the answer slightly.
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