FORESTRY
AGRICULTURAL STATISTICS AND ECONOMICS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Determine the minimum sample size needed to construct a 95% confidence interval for the mean age of employees at a company. The estimate must be accurate to within 0.5 year. Assume the standard deviation is 4.8 years.
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18
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19
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354
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355
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Explanation:
Detailed explanation-1: -Since 95% of values fall within two standard deviations of the mean according to the 68-95-99.7 Rule, simply add and subtract two standard deviations from the mean in order to obtain the 95% confidence interval.
Detailed explanation-2: -Find the minimum sample size required to estimate the proportion to within three percentage points, at 90% confidence. Solution: Confidence level 90% means that =1−0.90=0.10 so ∕2=0.05.
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