Answer:
The 90% confidence interval is
Explanation:
From the question we are told that
The population standard deviation is

The sample mean is

The sample size is n = 669
From the question we are told the confidence level is 95% , hence the level of significance is
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Generally from the normal distribution table the critical value of
is
Generally the margin of error is mathematically represented as
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Generally 90% confidence interval is mathematically represented as
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