3.6.Interval Estimators - Case 2

Unit 3 - Estimation

3.6.Interval Estimators
3.6.2.Case 2: (1- α ) % Interval estimates for population proportion is given by,
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Where : p is the sample proportion and
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The maximum error E given by:
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Example 1
If the sample size is 64 individuals, and the percentage of female individuals in the sample is 35%, determine using a significance level of 1%, the corresponding confidence interval for the proportion of the female in population.
Solution
α = 0.01;
1 − α = 0.99;
zα/2 = 2.575.
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Example 2

In a sample of 400 selected at random, a sample mean of 50 was obtained. Determine the confidence interval with a confidence level of 97% for the average population.
Solution:
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Example 3
With the same confidence level, what minimum sample size should it have so that the interval width has a maximum length of 1?
Solution
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Last modified: Monday, 12 September 2011, 10:45 AM