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# A simple random sample of 80 customers is selected from an account receivable portfolio and the sample mean account balance is \$1250. The population...

1. A simple random sample of 80 customers is selected from an account receivable portfolio and the sample mean account balance is \$1250. The population standard deviation σ is known to be \$250. (8 points)
2. Construct a 95% confidence interval for the mean account balance of the population.
3. What is the margin of error for estimating the mean account balance at the 95% confidence level.
4. Construct a 95% confidence interval for the mean account balance of the population if the sample mean account balance is obtained from a random sample of 150 instead of 80.
5. Based on the results from a. and c., what can you say about the effect of a larger sample size on the length of the confidence interval at the same confidence level?

for sample size 80, 95% confidence interval is (1195.2163, 1304.7837) for sample... View the full answer

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