Answer: The interval is 0.9 ± 0.0259 and margin of error is 0.0259
Step-by-step explanation: <em>Confidence interval for a proportion in one sample</em> is the estimate of the proportion of a population. It is calculated following the next steps:
1) Find the proportion , in which x is the number of people with the desired condition. In our case, p=0.9;
2) Calculate margin of error, i.e.:
z is z-score, which for a 95% confidence, equals 1.96;
Substituting with the data given:
= 0.0259
3) Write: p ±
In our case, the interval will be 0.9 ± 0.0259.
<u><em>Margin</em></u><em> </em><u><em>of</em></u><em> </em><u><em>error</em></u> is the random sampling error in the results of a survey, i.e.,it shows you how far your result will be from the real value. For the Harris poll, margin of error is 0.0259