- 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**) - Construct a 95% confidence interval for the mean account balance of the population.
- What is the margin of error for estimating the mean account balance at the 95% confidence level.
- 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.
- 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?

#### Top Answer

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