Confidence Interval for means

1. Sixty small loan applications in a bank were randomly selected for the purpose of determining the average dollar amount requested for each loan. The results of the sample reveal a mean of $450 and a standard deviation of $75 and the population is normally distributed.

Construct a 95% Confidence Interval for the true population mean dollar amount requested

for each loan. Briefly interpret the confidence interval constructed

2. In a city X, the average weight of 60 persons is 195lbs. The standard deviation of the measurement is 3.8. Construct a 90% confidence interval for the population mean, Interpret

the result.

3. A survey of 40 adults revealed a mean height of 150cm. assuming the standard deviation of the heights in the population is 8 years. What is the 99% confidence interval of the population mean height? Interpret the result.

4. A survey of 20 adults revealed a mean age of 50 years. Assuming the standard deviation of the ages is 10 years. What is the 90% confidence interval of the population mean age? Interpret the result.