We consider, from a population of traders, a random sample of size n=40. We focus on their annual bonus and find a sample mean of $300,000. We assume that the population variance is known and equal to 82,000. Find the 95% confidence interval for the population mean.

300,000 1.96 82,000 / 40

300,000 2.06 82,000 / 40

300,000 1.65 82,000 / 40

300,000 1.28 82,000 / 40

Which one is true ?

We consider, from a population of traders, a random sample of size n=40. We focus on their annual bonus and find a sample mean of $300,000 and a sample standard deviation of $80,000. Find the 95% confidence interval for the population mean.

300,000 2.02 80,000 / 39

300,000 1.96 80,000 / 40

300,000 1.68 80,000 / 40

300,000 2.02 80,000 / 40

Which one is true ?